diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index e0d8ade..4a74619 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -30,9 +30,6 @@ jobs:
 
     - uses: Swatinem/rust-cache@v1
 
-    - name: Check Lockfile
-      run: cargo update --locked --package just
-
     - name: Clippy
       run: cargo clippy --all --all-targets
 
diff --git a/README.md b/README.md
index e99aff0..18bae44 100644
--- a/README.md
+++ b/README.md
@@ -2175,6 +2175,47 @@ But they must match:
 $ just foo/a bar/b
 error: Conflicting path arguments: `foo/` and `bar/`
 ```
+### Include Directives
+
+The `!include` directive, currently unstable, can be used to include the
+verbatim text of another file.
+
+If you have the following `justfile`:
+
+```mf
+!include foo/bar.just
+
+a: b
+  @echo A
+
+```
+
+And the following text in `foo/bar.just`:
+
+```mf
+b:
+  @echo B
+```
+
+`foo/bar.just` will be included in `justfile` and recipe `b` will be defined:
+
+```sh
+$ just --unstable b
+B
+$ just --unstable a
+B
+A
+```
+
+The `!include` directive path can be absolute or relative to the location of
+the justfile containing it. `!include` directives must appear at the beginning
+of a line. line.
+
+`!include` directives are only processed before the first non-blank,
+non-comment line.
+
+Included files can themselves contain `!include` directives, which are
+processed recursively.
 
 ### Hiding `justfile`s
 
diff --git a/src/error.rs b/src/error.rs
index 15e42b9..54bebc8 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -31,6 +31,10 @@ pub(crate) enum Error<'src> {
     chooser: OsString,
     io_error: io::Error,
   },
+  CircularInclude {
+    current: PathBuf,
+    include: PathBuf,
+  },
   Code {
     recipe: &'src str,
     line_number: Option<usize>,
@@ -84,12 +88,19 @@ pub(crate) enum Error<'src> {
     function: Name<'src>,
     message: String,
   },
+  IncludeMissingPath {
+    file: PathBuf,
+    line: usize,
+  },
   InitExists {
     justfile: PathBuf,
   },
   Internal {
     message: String,
   },
+  InvalidDirective {
+    line: String,
+  },
   Io {
     recipe: &'src str,
     io_error: io::Error,
@@ -330,6 +341,12 @@ impl<'src> ColorDisplay for Error<'src> {
           io_error
         )?;
       }
+      CircularInclude { current, include } => {
+        write!(
+          f,
+          "Include `{}` in `{}` is a circular include", include.display(), current.display()
+        )?;
+      },
       Code {
         recipe,
         line_number,
@@ -482,6 +499,18 @@ impl<'src> ColorDisplay for Error<'src> {
           message
         )?;
       }
+      IncludeMissingPath {
+        file: justfile, line
+      } => {
+
+        write!(
+          f,
+          "!include directive on line {} of `{}` has no argument",
+          line.ordinal(),
+          justfile.display(),
+        )?;
+
+      },
       InitExists { justfile } => {
         write!(f, "Justfile `{}` already exists", justfile.display())?;
       }
@@ -493,6 +522,9 @@ impl<'src> ColorDisplay for Error<'src> {
           message
         )?;
       }
+      InvalidDirective { line } => {
+        write!(f, "Invalid directive: {line}")?;
+      }
       Io { recipe, io_error } => {
         match io_error.kind() {
           io::ErrorKind::NotFound => write!(
diff --git a/src/loader.rs b/src/loader.rs
index 95fa7c3..7ea5612 100644
--- a/src/loader.rs
+++ b/src/loader.rs
@@ -1,21 +1,216 @@
 use super::*;
+use std::collections::HashSet;
+
+struct LinesWithEndings<'a> {
+  input: &'a str,
+}
+
+impl<'a> LinesWithEndings<'a> {
+  fn new(input: &'a str) -> Self {
+    Self { input }
+  }
+}
+
+impl<'a> Iterator for LinesWithEndings<'a> {
+  type Item = &'a str;
+
+  fn next(&mut self) -> Option<&'a str> {
+    if self.input.is_empty() {
+      return None;
+    }
+    let split = self.input.find('\n').map_or(self.input.len(), |i| i + 1);
+    let (line, rest) = self.input.split_at(split);
+    self.input = rest;
+    Some(line)
+  }
+}
 
 pub(crate) struct Loader {
   arena: Arena<String>,
+  unstable: bool,
 }
 
 impl Loader {
-  pub(crate) fn new() -> Self {
+  pub(crate) fn new(unstable: bool) -> Self {
     Loader {
       arena: Arena::new(),
+      unstable,
     }
   }
 
   pub(crate) fn load<'src>(&'src self, path: &Path) -> RunResult<&'src str> {
-    let src = fs::read_to_string(path).map_err(|io_error| Error::Load {
-      path: path.to_owned(),
-      io_error,
-    })?;
+    let src = self.load_recursive(path, HashSet::new())?;
     Ok(self.arena.alloc(src))
   }
+
+  fn load_file<'a>(path: &Path) -> RunResult<'a, String> {
+    fs::read_to_string(path).map_err(|io_error| Error::Load {
+      path: path.to_owned(),
+      io_error,
+    })
+  }
+
+  fn load_recursive(&self, file: &Path, seen: HashSet<PathBuf>) -> RunResult<String> {
+    let src = Self::load_file(file)?;
+
+    let mut output = String::new();
+
+    let mut seen_content = false;
+
+    for (i, line) in LinesWithEndings::new(&src).enumerate() {
+      if !seen_content && line.starts_with('!') {
+        let include = line
+          .strip_prefix("!include")
+          .ok_or_else(|| Error::InvalidDirective { line: line.into() })?;
+
+        if !self.unstable {
+          return Err(Error::Unstable {
+            message: "The !include directive is currently unstable.".into(),
+          });
+        }
+
+        let argument = include.trim();
+
+        if argument.is_empty() {
+          return Err(Error::IncludeMissingPath {
+            file: file.to_owned(),
+            line: i,
+          });
+        }
+
+        let contents = self.process_include(file, Path::new(argument), &seen)?;
+
+        output.push_str(&contents);
+      } else {
+        if !(line.trim().is_empty() || line.trim().starts_with('#')) {
+          seen_content = true;
+        }
+        output.push_str(line);
+      }
+    }
+
+    Ok(output)
+  }
+
+  fn process_include(
+    &self,
+    file: &Path,
+    include: &Path,
+    seen: &HashSet<PathBuf>,
+  ) -> RunResult<String> {
+    let canonical_path = if include.is_relative() {
+      let current_dir = file.parent().ok_or(Error::Internal {
+        message: format!(
+          "Justfile path `{}` has no parent directory",
+          include.display()
+        ),
+      })?;
+      current_dir.join(include)
+    } else {
+      include.to_owned()
+    };
+
+    let canonical_path = canonical_path.lexiclean();
+
+    if seen.contains(&canonical_path) {
+      return Err(Error::CircularInclude {
+        current: file.to_owned(),
+        include: canonical_path,
+      });
+    }
+
+    let mut seen_paths = seen.clone();
+    seen_paths.insert(file.lexiclean());
+
+    self.load_recursive(&canonical_path, seen_paths)
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::{Error, Lexiclean, Loader};
+  use temptree::temptree;
+
+  #[test]
+  fn include_justfile() {
+    let justfile_a = r#"
+# A comment at the top of the file
+!include ./justfile_b
+
+some_recipe: recipe_b
+    echo "some recipe"
+"#;
+
+    let justfile_b = r#"!include ./subdir/justfile_c
+
+recipe_b: recipe_c
+    echo "recipe b"
+"#;
+
+    let justfile_c = r#"recipe_c:
+    echo "recipe c"
+"#;
+
+    let tmp = temptree! {
+        justfile: justfile_a,
+        justfile_b: justfile_b,
+        subdir: {
+            justfile_c: justfile_c
+        }
+    };
+
+    let full_concatenated_output = r#"
+# A comment at the top of the file
+recipe_c:
+    echo "recipe c"
+
+recipe_b: recipe_c
+    echo "recipe b"
+
+some_recipe: recipe_b
+    echo "some recipe"
+"#;
+
+    let loader = Loader::new(true);
+
+    let justfile_a_path = tmp.path().join("justfile");
+    let loader_output = loader.load(&justfile_a_path).unwrap();
+
+    assert_eq!(loader_output, full_concatenated_output);
+  }
+
+  #[test]
+  fn recursive_includes_fail() {
+    let justfile_a = r#"
+# A comment at the top of the file
+!include ./subdir/justfile_b
+
+some_recipe: recipe_b
+    echo "some recipe"
+
+"#;
+
+    let justfile_b = r#"
+!include ../justfile
+
+recipe_b:
+    echo "recipe b"
+"#;
+    let tmp = temptree! {
+        justfile: justfile_a,
+        subdir: {
+            justfile_b: justfile_b
+        }
+    };
+
+    let loader = Loader::new(true);
+
+    let justfile_a_path = tmp.path().join("justfile");
+    let loader_output = loader.load(&justfile_a_path).unwrap_err();
+
+    assert_matches!(loader_output, Error::CircularInclude { current, include }
+        if current == tmp.path().join("subdir").join("justfile_b").lexiclean() &&
+        include == tmp.path().join("justfile").lexiclean()
+    );
+  }
 }
diff --git a/src/run.rs b/src/run.rs
index 950fa0b..a1a18c2 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -17,14 +17,14 @@ pub fn run() -> Result<(), i32> {
   info!("Parsing command line arguments…");
   let matches = app.get_matches();
 
-  let loader = Loader::new();
-
   let config = Config::from_matches(&matches).map_err(Error::from);
 
-  let (color, verbosity) = config
+  let (color, verbosity, unstable) = config
     .as_ref()
-    .map(|config| (config.color, config.verbosity))
-    .unwrap_or((Color::auto(), Verbosity::default()));
+    .map(|config| (config.color, config.verbosity, config.unstable))
+    .unwrap_or((Color::auto(), Verbosity::default(), false));
+
+  let loader = Loader::new(unstable);
 
   config
     .and_then(|config| config.run(&loader))
diff --git a/tests/choose.rs b/tests/choose.rs
index d89c31b..b7e9f44 100644
--- a/tests/choose.rs
+++ b/tests/choose.rs
@@ -125,7 +125,7 @@ fn invoke_error_function() {
           echo bar
       ",
     )
-    .stderr_regex("error: Chooser `/ -cu fzf` invocation failed: .*")
+    .stderr_regex("error: Chooser `/ -cu fzf` invocation failed: .*\n")
     .status(EXIT_FAILURE)
     .shell(false)
     .args(["--shell", "/", "--choose"])
diff --git a/tests/error_messages.rs b/tests/error_messages.rs
index 8e5fb36..e17a4af 100644
--- a/tests/error_messages.rs
+++ b/tests/error_messages.rs
@@ -26,11 +26,11 @@ test! {
 
 test! {
   name: unexpected_character,
-  justfile: "!~",
+  justfile: "&~",
   stderr: "
-    error: Expected character `=`
+    error: Expected character `&`
       |
-    1 | !~
+    1 | &~
       |  ^
   ",
   status: EXIT_FAILURE,
diff --git a/tests/includes.rs b/tests/includes.rs
new file mode 100644
index 0000000..8850b9b
--- /dev/null
+++ b/tests/includes.rs
@@ -0,0 +1,91 @@
+use super::*;
+
+#[test]
+fn include_fails_without_unstable() {
+  Test::new()
+    .justfile("!include ./include.justfile")
+    .status(EXIT_FAILURE)
+    .stderr("error: The !include directive is currently unstable. Invoke `just` with the `--unstable` flag to enable unstable features.\n")
+    .run();
+}
+
+#[test]
+fn include_succeeds_with_unstable() {
+  Test::new()
+    .tree(tree! {
+      "include.justfile": "
+        b:
+          @echo B
+      ",
+    })
+    .justfile(
+      "
+        !include ./include.justfile
+
+        a: b
+          @echo A
+      ",
+    )
+    .arg("--unstable")
+    .test_round_trip(false)
+    .arg("a")
+    .stdout("B\nA\n")
+    .run();
+}
+
+#[test]
+fn trailing_spaces_after_include_are_ignored() {
+  Test::new()
+    .tree(tree! {
+      "include.justfile": "
+        a:
+          @echo A
+      ",
+    })
+    .justfile("!include ./include.justfile\x20")
+    .arg("--unstable")
+    .test_round_trip(false)
+    .stdout("A\n")
+    .run();
+}
+
+#[test]
+fn include_directive_with_no_path() {
+  Test::new()
+    .justfile("!include")
+    .arg("--unstable")
+    .status(EXIT_FAILURE)
+    .stderr_regex("error: !include directive on line 1 of `.*` has no argument\n")
+    .run();
+}
+
+#[test]
+fn trailing_include() {
+  Test::new()
+    .justfile(
+      "
+      b:
+      !include ./include.justfile
+      ",
+    )
+    .arg("--unstable")
+    .status(EXIT_FAILURE)
+    .stderr("error: Expected character `=`\n  |\n2 | !include ./include.justfile\n  |  ^\n")
+    .run();
+}
+
+#[test]
+fn circular_include() {
+  Test::new()
+    .justfile("!include a")
+    .tree(tree! {
+      a: "!include b",
+      b: "!include a",
+    })
+    .arg("--unstable")
+    .status(EXIT_FAILURE)
+    .stderr_regex(path_for_regex(
+      "error: Include `.*/a` in `.*/b` is a circular include\n",
+    ))
+    .run();
+}
diff --git a/tests/lib.rs b/tests/lib.rs
index 29ddf2c..6dbc733 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -51,6 +51,7 @@ mod fallback;
 mod fmt;
 mod functions;
 mod ignore_comments;
+mod includes;
 mod init;
 #[cfg(unix)]
 mod interrupts;
@@ -93,3 +94,11 @@ fn path(s: &str) -> String {
     s.into()
   }
 }
+
+fn path_for_regex(s: &str) -> String {
+  if cfg!(windows) {
+    s.replace('/', "\\\\")
+  } else {
+    s.into()
+  }
+}
diff --git a/tests/test.rs b/tests/test.rs
index 62bc089..8271074 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -47,6 +47,7 @@ pub(crate) struct Test {
   pub(crate) stdout: String,
   pub(crate) stdout_regex: Option<Regex>,
   pub(crate) tempdir: TempDir,
+  pub(crate) test_round_trip: bool,
   pub(crate) unindent_stdout: bool,
 }
 
@@ -69,6 +70,7 @@ impl Test {
       stdout: String::new(),
       stdout_regex: None,
       tempdir,
+      test_round_trip: true,
       unindent_stdout: true,
     }
   }
@@ -125,7 +127,7 @@ impl Test {
   }
 
   pub(crate) fn stderr_regex(mut self, stderr_regex: impl AsRef<str>) -> Self {
-    self.stderr_regex = Some(Regex::new(&format!("(?m)^{}$", stderr_regex.as_ref())).unwrap());
+    self.stderr_regex = Some(Regex::new(&format!("^{}$", stderr_regex.as_ref())).unwrap());
     self
   }
 
@@ -140,7 +142,12 @@ impl Test {
   }
 
   pub(crate) fn stdout_regex(mut self, stdout_regex: impl AsRef<str>) -> Self {
-    self.stdout_regex = Some(Regex::new(&format!("(?m)^{}$", stdout_regex.as_ref())).unwrap());
+    self.stdout_regex = Some(Regex::new(&format!("^{}$", stdout_regex.as_ref())).unwrap());
+    self
+  }
+
+  pub(crate) fn test_round_trip(mut self, test_round_trip: bool) -> Self {
+    self.test_round_trip = test_round_trip;
     self
   }
 
@@ -245,7 +252,7 @@ impl Test {
       panic!("Output mismatch.");
     }
 
-    if self.status == EXIT_SUCCESS {
+    if self.test_round_trip && self.status == EXIT_SUCCESS {
       test_round_trip(self.tempdir.path());
     }