diff --git a/rules/aip0123/resource_type_name.go b/rules/aip0123/resource_type_name.go
index 41971c6cd..42c960c6f 100644
--- a/rules/aip0123/resource_type_name.go
+++ b/rules/aip0123/resource_type_name.go
@@ -15,7 +15,10 @@
 package aip0123
 
 import (
+	"fmt"
+	"regexp"
 	"strings"
+	"unicode"
 
 	"github.com/googleapis/api-linter/lint"
 	"github.com/googleapis/api-linter/locations"
@@ -23,6 +26,10 @@ import (
 	"github.com/jhump/protoreflect/desc"
 )
 
+var (
+	resourceNameRegex = regexp.MustCompile(`^[\p{L}A-Za-z0-9]+$`)
+)
+
 var resourceTypeName = &lint.MessageRule{
 	Name: lint.NewRuleName(123, "resource-type-name"),
 	OnlyIf: func(m *desc.MessageDescriptor) bool {
@@ -30,14 +37,31 @@ var resourceTypeName = &lint.MessageRule{
 	},
 	LintMessage: func(m *desc.MessageDescriptor) []lint.Problem {
 		resource := utils.GetResource(m)
-		if strings.Count(resource.GetType(), "/") != 1 {
+		resourceType := resource.GetType()
+		if strings.Count(resourceType, "/") != 1 {
 			return []lint.Problem{{
 				Message:    "Resource type names must be of the form {Service Name}/{Type}.",
 				Descriptor: m,
 				Location:   locations.MessageResource(m),
 			}}
 		}
-
+		typeName := strings.Split(resourceType, "/")[1]
+		if !unicode.IsUpper(rune(typeName[0])) {
+			return []lint.Problem{{
+				Message:    fmt.Sprintf("Type %q must be UpperCamelCase", typeName),
+				Descriptor: m,
+				Location:   locations.MessageResource(m),
+			}}
+		}
+		if !resourceNameRegex.MatchString(typeName) {
+			return []lint.Problem{{
+				Message: fmt.Sprintf(
+					"Type %q must only contain alphanumeric characters", typeName,
+				),
+				Descriptor: m,
+				Location:   locations.MessageResource(m),
+			}}
+		}
 		return nil
 	},
 }
diff --git a/rules/aip0123/resource_type_name_test.go b/rules/aip0123/resource_type_name_test.go
index 45670e584..f6038ba8f 100644
--- a/rules/aip0123/resource_type_name_test.go
+++ b/rules/aip0123/resource_type_name_test.go
@@ -27,8 +27,12 @@ func TestResourceTypeName(t *testing.T) {
 		problems testutils.Problems
 	}{
 		{"Valid", "library.googleapis.com/Book", testutils.Problems{}},
+		{"ValidWithUnicode", "library.googleapis.com/BoØkLibre", testutils.Problems{}},
 		{"InvalidTooMany", "library.googleapis.com/shelf/Book", testutils.Problems{{Message: "{Service Name}/{Type}"}}},
 		{"InvalidNotEnough", "library.googleapis.com~Book", testutils.Problems{{Message: "{Service Name}/{Type}"}}},
+		{"InvalidLowerCamelCase", "library.googleapis.com/bookLoan", testutils.Problems{{Message: "Type \"bookLoan\" must be UpperCamelCase"}}},
+		{"InvalidTypeNotAlphaNumeric", "library.googleapis.com/Book.:3", testutils.Problems{{Message: "Type \"Book.:3\" must only contain alphanumeric characters"}}},
+		{"InvalidTypeContainsEmoji", "library.googleapis.com/Book♥️", testutils.Problems{{Message: "Type \"Book♥️\" must only contain alphanumeric characters"}}},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			f := testutils.ParseProto3Tmpl(t, `