diff --git a/src/config.rs b/src/config.rs
index 761068e..fa603c8 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -93,7 +93,12 @@ impl TryFrom<Document> for Config {
                     bc.auth.insert(s);
                 }
                 Element::Fork => bc.fork = true,
-                Element::Include(_) => { /* no-op */ }
+                Element::Include(_) => {
+                    // NO-OP: removed during `Document::resolve_includes`
+                }
+                Element::Includedir(_) => {
+                    // NO-OP: removed during `Document::resolve_includedirs`
+                }
                 Element::KeepUmask => bc.keep_umask = true,
                 Element::Limit => {
                     warn!("warning: busd does not implement `<limit>`");
diff --git a/src/config/xml.rs b/src/config/xml.rs
index 10c0d67..908b3d4 100644
--- a/src/config/xml.rs
+++ b/src/config/xml.rs
@@ -1,6 +1,7 @@
 use std::{
     env::current_dir,
-    fs::read_to_string,
+    ffi::OsString,
+    fs::{read_dir, read_to_string},
     path::{Path, PathBuf},
     str::FromStr,
 };
@@ -36,7 +37,47 @@ impl Document {
 
         let mut doc = Document::from_str(&text)?;
         doc.file_path = Some(file_path.as_ref().to_path_buf());
-        doc.resolve_includes()
+        doc.resolve_includedirs()?.resolve_includes()
+    }
+
+    fn resolve_includedirs(self) -> Result<Document> {
+        let base_path = self.base_path()?;
+        let Document {
+            busconfig,
+            file_path,
+        } = self;
+
+        let mut doc = Document {
+            busconfig: vec![],
+            file_path: None,
+        };
+
+        for el in busconfig {
+            match el {
+                Element::Includedir(dir_path) => {
+                    let dir_path = match resolve_include_path(&base_path, &dir_path) {
+                        Ok(ok) => ok,
+                        Err(err) => {
+                            error!("'{}' should be a valid file path", dir_path.display());
+                            return Err(err);
+                        }
+                    };
+                    for entry in read_dir(dir_path)? {
+                        let path = entry?.path();
+                        if path.extension() == Some(&OsString::from("conf")) && path.is_file() {
+                            doc.busconfig.push(Element::Include(IncludeElement {
+                                file_path: path,
+                                ..Default::default()
+                            }));
+                        }
+                    }
+                }
+                _ => doc.busconfig.push(el),
+            }
+        }
+
+        doc.file_path = file_path;
+        Ok(doc)
     }
 
     fn resolve_includes(self) -> Result<Document> {
@@ -117,7 +158,7 @@ pub enum Element {
     Auth(String),
     Fork,
     Include(IncludeElement),
-    // TODO: support `<includedir>`
+    Includedir(PathBuf),
     KeepUmask,
     Listen(String),
     Limit,
diff --git a/tests/config.rs b/tests/config.rs
index 83a283f..1643a56 100644
--- a/tests/config.rs
+++ b/tests/config.rs
@@ -12,8 +12,11 @@ fn config_read_file_with_includes_ok() {
         Config {
             auth: HashSet::from_iter(vec![String::from("ANONYMOUS"), String::from("EXTERNAL"),]),
             listen: HashSet::from_iter(vec![
+                String::from("unix:path=/tmp/a"), // via <includedir>
+                String::from("unix:path=/tmp/b"), // via <includedir>
+                // should be no "unix:path=/tmp/not_included" as that file ends in .xml
                 String::from("unix:path=/tmp/foo"),
-                String::from("tcp:host=localhost,port=1234"),
+                String::from("tcp:host=localhost,port=1234"), // via <include>
             ]),
             policies: vec![
                 Policy::DefaultContext(vec![
@@ -63,3 +66,10 @@ fn config_read_file_with_transitive_missing_include_err() {
     Config::read_file("./tests/fixtures/transitive_missing_include.conf")
         .expect("should read and parse XML input");
 }
+
+#[should_panic]
+#[test]
+fn config_read_file_with_missing_includedir_err() {
+    Config::read_file("./tests/fixtures/missing_includedir.conf")
+        .expect("should read and parse XML input");
+}
diff --git a/tests/fixtures/includedir/a.conf b/tests/fixtures/includedir/a.conf
new file mode 100644
index 0000000..d602268
--- /dev/null
+++ b/tests/fixtures/includedir/a.conf
@@ -0,0 +1,5 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <listen>unix:path=/tmp/a</listen>
+</busconfig>
diff --git a/tests/fixtures/includedir/b.conf b/tests/fixtures/includedir/b.conf
new file mode 100644
index 0000000..d351cfe
--- /dev/null
+++ b/tests/fixtures/includedir/b.conf
@@ -0,0 +1,5 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <listen>unix:path=/tmp/b</listen>
+</busconfig>
diff --git a/tests/fixtures/includedir/not_included.xml b/tests/fixtures/includedir/not_included.xml
new file mode 100644
index 0000000..5af9363
--- /dev/null
+++ b/tests/fixtures/includedir/not_included.xml
@@ -0,0 +1,5 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <listen>unix:path=/tmp/not_included</listen>
+</busconfig>
diff --git a/tests/fixtures/missing_includedir.conf b/tests/fixtures/missing_includedir.conf
new file mode 100644
index 0000000..01e2df1
--- /dev/null
+++ b/tests/fixtures/missing_includedir.conf
@@ -0,0 +1,5 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <includedir>./missing</includedir>
+</busconfig>
diff --git a/tests/fixtures/valid.conf b/tests/fixtures/valid.conf
index 7a20a08..f8e2a00 100644
--- a/tests/fixtures/valid.conf
+++ b/tests/fixtures/valid.conf
@@ -9,4 +9,5 @@
     </policy>
     <include>./valid_included.conf</include>
     <include ignore_missing="yes">./valid_missing.conf</include>
+    <includedir>./includedir</includedir>
 </busconfig>