diff --git a/src/abstractdataarray.jl b/src/abstractdataarray.jl
index b2ce25c..b09dc92 100644
--- a/src/abstractdataarray.jl
+++ b/src/abstractdataarray.jl
@@ -4,7 +4,7 @@
 An `N`-dimensional `AbstractArray` whose entries can take on values of type
 `T` or the value `NA`.
 """
-abstract type AbstractDataArray{T, N} <: AbstractArray{T, N} end
+abstract type AbstractDataArray{T, N} <: AbstractArray{Data{T}, N} end
 
 """
     AbstractDataVector{T}
@@ -20,7 +20,7 @@ A 2-dimensional [`AbstractDataArray`](@ref) with element type `T`.
 """
 const AbstractDataMatrix{T} = AbstractDataArray{T, 2}
 
-Base.eltype(d::AbstractDataArray{T, N}) where {T, N} = T
+Base.eltype(d::AbstractDataArray{T, N}) where {T, N} = Union{T,NAtype}
 
 # Generic iteration over AbstractDataArray's
 
diff --git a/src/broadcast.jl b/src/broadcast.jl
index 3dfe817..d38a369 100644
--- a/src/broadcast.jl
+++ b/src/broadcast.jl
@@ -189,9 +189,30 @@ Base.Broadcast._containertype(::Type{T}) where T<:DataArray           = DataArra
 Base.Broadcast._containertype(::Type{T}) where T<:PooledDataArray     = PooledDataArray
 Base.Broadcast.broadcast_indices(::Type{T}, A) where T<:AbstractDataArray = indices(A)
 
+@inline function broadcast_t(f, ::Type{T}, shape, A, Bs...) where {T}
+    dest = Base.Broadcast.containertype(A, Bs...)(extractT(T), Base.index_lengths(shape...))
+    return broadcast!(f, dest, A, Bs...)
+end
+
+# This is mainly to handle isna.(x) since isna is probably the only
+# function that can guarantee that NAs will never propagate
+@inline function broadcast_t(f, ::Type{Bool}, shape, A, Bs...)
+    dest = similar(BitArray, shape)
+    return broadcast!(f, dest, A, Bs...)
+end
+
+# This one is almost identical to the version in Base and can hopefully be
+# removed at some point. The main issue in Base is that it tests for
+# isleaftype(T) which is false for Union{T,NAtype}. If the test in Base
+# can be modified to cover simple unions of leaftypes then this method
+# can probably be deleted and the two _t methods adjusted to match the Base
+# invokation from Base.Broadcast.broadcast_c
 @inline function Base.Broadcast.broadcast_c{S<:AbstractDataArray}(f, ::Type{S}, A, Bs...)
     T     = Base.Broadcast._broadcast_eltype(f, A, Bs...)
     shape = Base.Broadcast.broadcast_indices(A, Bs...)
-    dest = S(T, Base.index_lengths(shape...))
-    return broadcast!(f, dest, A, Bs...)
+    return broadcast_t(f, T, shape, A, Bs...)
 end
+
+# This one is much faster than normal broadcasting but the method won't get called
+# in fusing operations like (!).(isna.(x))
+Base.broadcast(::typeof(isna), da::DataArray) = copy(da.na)
diff --git a/src/dataarray.jl b/src/dataarray.jl
index 83451c1..2e4617a 100644
--- a/src/dataarray.jl
+++ b/src/dataarray.jl
@@ -162,7 +162,7 @@ function Base.resize!(da::DataArray{T,1}, n::Int) where T
 end
 
 function Base.similar(da::DataArray, T::Type, dims::Dims) #-> DataArray{T}
-    return DataArray(Array{T}(dims), trues(dims))
+    return DataArray(Array{extractT(T)}(dims), trues(dims))
 end
 
 Base.size(d::DataArray) = size(d.data) # -> (Int...)
@@ -244,8 +244,6 @@ end
 
 dropna(dv::DataVector) = dv.data[.!dv.na] # -> Vector
 
-Base.broadcast(::typeof(isna), da::DataArray) = copy(da.na)
-
 Base.any(::typeof(isna), da::DataArray) = any(da.na) # -> Bool
 Base.all(::typeof(isna), da::DataArray) = all(da.na) # -> Bool
 
diff --git a/src/extras.jl b/src/extras.jl
index 5ed5175..b35670c 100644
--- a/src/extras.jl
+++ b/src/extras.jl
@@ -19,12 +19,13 @@ function StatsBase.addcounts!(cm::Dict{U,W}, x::AbstractDataArray{T}, wv::Weight
     return cm
 end
 
-function StatsBase.countmap(x::AbstractDataArray{T}) where T
-    addcounts!(Dict{Union{T, NAtype}, Int}(), x)
+
+function StatsBase.countmap(x::AbstractDataArray{T}) where {T}
+    addcounts!(Dict{Data{T}, Int}(), x)
 end
 
 function StatsBase.countmap(x::AbstractDataArray{T}, wv::Weights{W}) where {T,W}
-    addcounts!(Dict{Union{T, NAtype}, W}(), x, wv)
+    addcounts!(Dict{Data{T}, W}(), x, wv)
 end
 
 """
diff --git a/src/natype.jl b/src/natype.jl
index 6f99ac5..ab55f06 100644
--- a/src/natype.jl
+++ b/src/natype.jl
@@ -29,6 +29,8 @@ A value denoting missingness within the domain of any type.
 """
 const NA = NAtype()
 
+const Data{T} = Union{T,NAtype}
+
 Base.show(io::IO, x::NAtype) = print(io, "NA")
 
 struct NAException <: Exception
@@ -36,12 +38,38 @@ struct NAException <: Exception
 end
 NAException() = NAException("NA found")
 
+# Restrict to Number to avoid infinite recursion
+# Might be possible to get rid of these restrictions if the promotion in base gets changed.
+## Numbers
+Base.promote_rule(::Type{Data{T}}, ::Type{Data{S}}) where {T<:Number,S<:Number} =
+    Union{promote_type(T, S),NAtype}
+Base.promote_rule(::Type{Data{T}}, ::Type{S}) where {T<:Number,S<:Number} =
+    Union{promote_type(T, S),NAtype}
+## Dates
+Base.promote_rule(::Type{Data{T}}, ::Type{Data{S}}) where {T<:Dates.AbstractTime,S<:Dates.AbstractTime} =
+    Union{promote_type(T, S),NAtype}
+Base.promote_rule(::Type{Data{T}}, ::Type{S}) where {T<:Dates.AbstractTime,S<:Dates.AbstractTime} =
+    Union{promote_type(T, S),NAtype}
+
+Base.promote_rule(::Type{NAtype}, ::Type{T}) where {T} = Union{T,NAtype}
+
+# Restrict to Number to avoid maching everything
+Base.convert(::Type{Data{T}}, x::Number)             where {T<:Number}             = convert(T, x)
+Base.convert(::Type{Data{T}}, x::Dates.AbstractTime) where {T<:Dates.AbstractTime} = convert(T, x)
+
 Base.length(x::NAtype) = 1
 Base.size(x::NAtype) = ()
 Base.size(x::NAtype, i::Integer) = i < 1 ? throw(BoundsError()) : 1
 Base.ndims(x::NAtype) = 0
 Base.getindex(x::NAtype, i) = i == 1 ? NA : throw(BoundsError())
 
+# extractT(::Type{Data{T}}) where {T} = T
+extractT(::Type{Union{T,NAtype}}) where {T} = T
+extractT(::Type{T}) where {T} = T
+extractT(::Type{NAtype}) = NAtype
+
+Base.zero(::Type{Data{T}}) where {T} = zero(T)
+
 """
     isna(x) -> Bool
 
@@ -60,7 +88,4 @@ true
 isna(x::NAtype) = true
 isna(x::Any) = false
 
-# TODO: Rethink this rule
-Base.promote_rule{T}(::Type{T}, ::Type{NAtype} ) = T
-
 Base.isnan(::NAtype) = NA
diff --git a/src/operators.jl b/src/operators.jl
index 2d602f6..1c5ad8b 100644
--- a/src/operators.jl
+++ b/src/operators.jl
@@ -205,6 +205,7 @@ for f in [:+,:-,:*,:/]
 end
 
 # Unary operators, DataArrays.
+@dataarray_unary(+, Any, T)
 @dataarray_unary(-, Bool, Int)
 @dataarray_unary(-, Any, T)
 @dataarray_unary(!, Bool, T)
@@ -531,31 +532,31 @@ function (-)(J::UniformScaling{TJ},A::DataArray{TA,2}) where {TA,TJ<:Number}
 end
 
 (+)(A::DataArray{Bool,2},J::UniformScaling{Bool}) =
-    invoke(+, Tuple{AbstractArray{Bool,2},UniformScaling{Bool}}, A, J)
+    invoke(+, Tuple{AbstractArray{Data{Bool},2},UniformScaling{Bool}}, A, J)
 (+)(J::UniformScaling{Bool},A::DataArray{Bool,2}) =
-    invoke(+, Tuple{UniformScaling{Bool},AbstractArray{Bool,2}}, J, A)
+    invoke(+, Tuple{UniformScaling{Bool},AbstractArray{Data{Bool},2}}, J, A)
 (-)(A::DataArray{Bool,2},J::UniformScaling{Bool}) =
-    invoke(-, Tuple{AbstractArray{Bool,2},UniformScaling{Bool}}, A, J)
+    invoke(-, Tuple{AbstractArray{Data{Bool},2},UniformScaling{Bool}}, A, J)
 (-)(J::UniformScaling{Bool},A::DataArray{Bool,2}) =
-    invoke(-, Tuple{UniformScaling{Bool},AbstractArray{Bool,2}}, J, A)
+    invoke(-, Tuple{UniformScaling{Bool},AbstractArray{Data{Bool},2}}, J, A)
 
 (+)(A::AbstractDataArray{TA,2},J::UniformScaling{TJ}) where {TA,TJ} =
-    invoke(+, Tuple{AbstractArray{TA,2},UniformScaling{TJ}}, A, J)
+    invoke(+, Tuple{AbstractArray{Data{TA},2},UniformScaling{TJ}}, A, J)
 (+)(J::UniformScaling,A::AbstractDataArray{TA,2}) where {TA} =
-    invoke(+, Tuple{UniformScaling,AbstractArray{TA,2}}, J, A)
+    invoke(+, Tuple{UniformScaling,AbstractArray{Data{TA},2}}, J, A)
 (-)(A::AbstractDataArray{TA,2},J::UniformScaling{TJ}) where {TA,TJ<:Number} =
-    invoke(-, Tuple{AbstractArray{TA,2},UniformScaling{TJ}}, A, J)
+    invoke(-, Tuple{AbstractArray{Data{TA},2},UniformScaling{TJ}}, A, J)
 (-)(J::UniformScaling{TJ},A::AbstractDataArray{TA,2}) where {TA,TJ<:Number} =
-    invoke(-, Tuple{UniformScaling{TJ},AbstractArray{TA,2}}, J, A)
+    invoke(-, Tuple{UniformScaling{TJ},AbstractArray{Data{TA},2}}, J, A)
 
 (+)(A::AbstractDataArray{Bool,2},J::UniformScaling{Bool}) =
-    invoke(+, Tuple{AbstractArray{Bool,2},UniformScaling{Bool}}, A, J)
+    invoke(+, Tuple{AbstractArray{Data{Bool},2},UniformScaling{Bool}}, A, J)
 (+)(J::UniformScaling{Bool},A::AbstractDataArray{Bool,2}) =
-    invoke(+, Tuple{UniformScaling{Bool},AbstractArray{Bool,2}}, J, A)
+    invoke(+, Tuple{UniformScaling{Bool},AbstractArray{Data{Bool},2}}, J, A)
 (-)(A::AbstractDataArray{Bool,2},J::UniformScaling{Bool}) =
-    invoke(-, Tuple{AbstractArray{Bool,2},UniformScaling{Bool}}, A, J)
+    invoke(-, Tuple{AbstractArray{Data{Bool},2},UniformScaling{Bool}}, A, J)
 (-)(J::UniformScaling{Bool},A::AbstractDataArray{Bool,2}) =
-    invoke(-, Tuple{UniformScaling{Bool},AbstractArray{Bool,2}}, J, A)
+    invoke(-, Tuple{UniformScaling{Bool},AbstractArray{Data{Bool},2}}, J, A)
 
 end # if isdefined(Base, :UniformScaling)
 
diff --git a/src/pooleddataarray.jl b/src/pooleddataarray.jl
index 068d739..fe8b13a 100644
--- a/src/pooleddataarray.jl
+++ b/src/pooleddataarray.jl
@@ -106,9 +106,9 @@ end
 PooledDataArray(d::PooledDataArray) = d
 
 # Constructor from array, w/ pool, missingness, and ref type
-function PooledDataArray(d::AbstractArray{T, N},
+function PooledDataArray(d::AbstractArray{<:Data{T}, N},
                          pool::Vector{T},
-                         m::AbstractArray{Bool, N},
+                         m::AbstractArray{<:Data{Bool}, N},
                          r::Type{R} = DEFAULT_POOLED_REF_TYPE) where {T,R<:Integer,N}
     if length(pool) > typemax(R)
         throw(ArgumentError("Cannot construct a PooledDataVector with type $R with a pool of size $(length(pool))"))
@@ -466,7 +466,7 @@ julia> p # has been modified
  "B"
 ```
 """
-function setlevels!(x::PooledDataArray{T,R}, newpool::AbstractVector{T}) where {T,R}
+function setlevels!(x::PooledDataArray{T,R}, newpool::AbstractVector) where {T,R}
     if newpool == myunique(newpool) # no NAs or duplicates
         x.pool = newpool
         return x
@@ -483,9 +483,6 @@ function setlevels!(x::PooledDataArray{T,R}, newpool::AbstractVector{T}) where {
     end
 end
 
-setlevels!(x::PooledDataArray{T, R},
-           newpool::AbstractVector) where {T, R} = setlevels!(x, convert(Array{T}, newpool))
-
 function setlevels(x::PooledDataArray, d::Dict)
     newpool = copy(DataArray(x.pool))
     # An NA in `v` is put in the pool; that will cause it to become NA
@@ -552,8 +549,9 @@ end
 ##
 ##############################################################################
 
+
 function Base.similar(pda::PooledDataArray{T,R}, S::Type, dims::Dims) where {T,R}
-    PooledDataArray(RefArray(zeros(R, dims)), S[])
+    PooledDataArray(RefArray(zeros(R, dims)), extractT(S)[])
 end
 
 ##############################################################################
diff --git a/src/reduce.jl b/src/reduce.jl
index 8e0f462..79dd322 100644
--- a/src/reduce.jl
+++ b/src/reduce.jl
@@ -162,7 +162,7 @@ Base.varm(A::DataArray{T}, m::NAtype; corrected::Bool=true, skipna::Bool=false)
 function Base.var(A::DataArray; corrected::Bool=true, mean=nothing, skipna::Bool=false)
     mean == 0 ? Base.varm(A, 0; corrected=corrected, skipna=skipna) :
     mean == nothing ? varm(A, Base.mean(A; skipna=skipna); corrected=corrected, skipna=skipna) :
-    isa(mean, Union{Number, NAtype}) ?
+    isa(mean, Data{Number}) ?
         varm(A, mean; corrected=corrected, skipna=skipna) :
         throw(ErrorException("Invalid value of mean."))
 end
diff --git a/src/reducedim.jl b/src/reducedim.jl
index 7de9071..f7bdcd6 100644
--- a/src/reducedim.jl
+++ b/src/reducedim.jl
@@ -302,8 +302,8 @@ end
 ## mean
 
 function Base.mean!(R::AbstractArray{T}, A::DataArray; skipna::Bool=false,
-                    init::Bool=true) where T
-    init && fill!(R, zero(eltype(R)))
+                       init::Bool=true) where {T}
+    init && fill!(R, 0)
     if skipna
         C = Array{Int}(size(R))
         _mapreducedim_skipna_impl!(identity, +, R, C, A)
diff --git a/src/statistics.jl b/src/statistics.jl
index 988c1c0..7236f69 100644
--- a/src/statistics.jl
+++ b/src/statistics.jl
@@ -39,13 +39,13 @@ gl(n::Integer, k::Integer) = gl(n, k, n*k)
 StatsBase.describe(X::DataVector) = StatsBase.describe(STDOUT, X)
 
 function StatsBase.describe(io::IO, X::AbstractDataVector{T}) where T<:Real
-    nacount = sum(isna.(X))
+    nacount = sum(isna, X)
     pna = 100nacount/length(X)
     if pna != 100 # describe will fail if dropna returns an empty vector
         describe(io, dropna(X))
     else
         println(io, "Summary Stats:")
-        println(io, "Type:           $(eltype(X))")
+        println(io, "Type:           $(T)")
     end
     println(io, "Number Missing: $(nacount)")
     @printf(io, "%% Missing:      %.6f\n", pna)
@@ -53,11 +53,11 @@ function StatsBase.describe(io::IO, X::AbstractDataVector{T}) where T<:Real
 end
 
 function StatsBase.describe(io::IO, X::AbstractDataVector)
-    nacount = sum(isna.(X))
+    nacount = sum(isna, X)
     pna = 100nacount/length(X)
     println(io, "Summary Stats:")
     println(io, "Length:         $(length(X))")
-    println(io, "Type:           $(eltype(X))")
+    println(io, "Type:           $(extractT(eltype(X)))")
     println(io, "Number Unique:  $(length(unique(X)))")
     println(io, "Number Missing: $(nacount)")
     @printf(io, "%% Missing:      %.6f\n", pna)
diff --git a/test/broadcast.jl b/test/broadcast.jl
index 26e7850..61e89ff 100644
--- a/test/broadcast.jl
+++ b/test/broadcast.jl
@@ -128,4 +128,12 @@
     @test map!(abs, x, x) == @data([1, 2])
     @test isequal(map!(+, DataArray(Float64, 3), @data([1, NA, 3]), @data([NA, 2, 3])), @data([NA, NA, 6]))
     @test map!(isequal, DataArray(Float64, 3), @data([1, NA, NA]), @data([1, NA, 3])) == @data([true, true, false])
+
+    # isna doesn't propagate NAs so it should return BitArrays
+    x = isna.(@data [NA, 1, 2])
+    @test x isa BitArray
+    @test x == [true, false, false]
+    x = (!).(isna.(@data [NA, 1, 2]))
+    @test x isa BitArray
+    @test x == [false, true, true]
 end
diff --git a/test/constructors.jl b/test/constructors.jl
index cb02688..6b7ee99 100644
--- a/test/constructors.jl
+++ b/test/constructors.jl
@@ -25,7 +25,7 @@
     @test isequal(dv, convert(DataArray, 1:3))
 
     dv = DataArray(Int, 3)
-    @test isequal(eltype(dv), Int)
+    @test isequal(eltype(dv), Data{Int})
     @test isequal(dv.na, trues(3))
 
     dv = convert(DataArray, zeros(3))
@@ -67,7 +67,7 @@
     @test isequal(pdv, convert(PooledDataArray, PooledDataArray([1, 2, 3])))
 
     pdv = PooledDataArray(Int, 3)
-    @test isequal(eltype(pdv), Int)
+    @test isequal(eltype(pdv), Data{Int})
     @test all(isna.(pdv) .== trues(3))
 
     pdv = convert(PooledDataArray, zeros(3))
@@ -106,7 +106,7 @@
     @test isequal(dm, convert(DataArray, trues(2, 2)))
 
     dm = DataArray(Int, 2, 2)
-    @test isequal(eltype(dm), Int)
+    @test isequal(eltype(dm), Data{Int})
     @test isequal(dm.na, trues(2, 2))
 
     @test_nowarn convert(DataArray, zeros(2, 2))
diff --git a/test/data.jl b/test/data.jl
index e8f7798..6796c30 100644
--- a/test/data.jl
+++ b/test/data.jl
@@ -71,13 +71,13 @@
     @test size(dvint) == (4,)
     @test length(dvint) == 4
     @test sum(isna.(dvint)) == 1
-    @test eltype(dvint) == Int
+    @test eltype(dvint) == Data{Int}
 
     #test_group("PooledDataVector methods")
     @test size(pdvstr) == (7,)
     @test length(pdvstr) == 7
     @test sum(isna.(pdvstr)) == 1
-    @test eltype(pdvstr) == String
+    @test eltype(pdvstr) == Data{String}
 
     #test_group("DataVector operations")
     @test isequal(dvint .+ 1, DataArray([2, 3, 4, 5], [false, false, true, false]))
@@ -99,7 +99,7 @@
     @test all(convert(Vector{Int}, dvint2) .== [5:8;])
     @test all([i + 1 for i in dvint2] .== [6:9;])
     @test all([length(x)::Int for x in dvstr] == [3, 3, 1, 4])
-    @test repr(dvint) == "[1, 2, NA, 4]"
+    @test repr(dvint) == "Union{DataArrays.NAtype, $Int}[1, 2, NA, 4]"
 
     #test_group("PooledDataVector to something else")
     @test all(dropna(pdvstr) .== ["one", "one", "two", "two", "one", "one"])
diff --git a/test/dataarray.jl b/test/dataarray.jl
index 7f483a5..e8597e8 100644
--- a/test/dataarray.jl
+++ b/test/dataarray.jl
@@ -99,7 +99,7 @@
     end
 
     # Inferrability of map (#276)
-    @test eltype(map(x -> x > 1, @data [1, 2])) == Bool
+    @test eltype(map(x -> x > 1, @data [1, 2])) == Data{Bool}
 
     @testset "Issue #278" begin
         x = @data ones(4)
diff --git a/test/extras.jl b/test/extras.jl
index 61f2327..1ecddb8 100644
--- a/test/extras.jl
+++ b/test/extras.jl
@@ -1,12 +1,14 @@
-@testset "Extras" begin
+# @testset "Extras" begin
     ##########
     ## countmap
     ##########
 
     d = @data [NA,3,3]
     w = weights([1.1,2.2,3.3])
-    cm = Dict{Union{Int, NAtype}, Int}([(NA, 1), (3, 2)])
-    cmw = Dict{Union{Int, NAtype}, Real}([(NA, 1.1), (3, 5.5)])
+    # cm = Dict{DataArrays.Data{Int}, Int}([(NA, 1), (3, 2)])
+    # cmw = Dict{DataArrays.Data{Int}, Real}([(NA, 1.1), (3, 5.5)])
+    cm = Dict{Union{NAtype,Int}, Int}([(NA, 1), (3, 2)])
+    cmw = Dict{Union{NAtype,Int}, Real}([(NA, 1.1), (3, 5.5)])
     @test isequal(countmap(d), cm)
     @test isequal(countmap(d, w), cmw)
 
@@ -44,4 +46,4 @@
     @test isequal(repeat(@pdata [:a :b NA]; inner = [2,1], outer = [1,3]),
                   @pdata [:a :b NA :a :b NA :a :b NA;
                           :a :b NA :a :b NA :a :b NA])
-end
+# end
diff --git a/test/nas.jl b/test/nas.jl
index 1152938..f80150c 100644
--- a/test/nas.jl
+++ b/test/nas.jl
@@ -62,4 +62,14 @@
     @test_throws NAException for v in each_failna(dv); end
     @test collect(each_dropna(dv)) == a
     @test collect(each_replacena(dv, 4)) == [4, 4, a..., 4]
+
+    @testset "promotion" for (T1, T2) in ((Int, Float64),
+                                          (Dates.Minute, Dates.Second))
+        @eval begin
+            @test promote_type($T1, Data{$T2})       == Data{$T2}
+            @test promote_type(Data{$T1}, $T2)       == Data{$T2}
+            @test promote_type(Data{$T1}, Data{$T2}) == Data{$T2}
+        end
+    end
+
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index d39730e..d9f3ef3 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -4,6 +4,7 @@
 
 using Base.Test
 using DataArrays
+using DataArrays: Data
 
 my_tests = ["abstractarray.jl",
             "booleans.jl",