diff --git a/src/header/spawn/cbindgen.toml b/src/header/spawn/cbindgen.toml
new file mode 100644
index 0000000..1db55cd
--- /dev/null
+++ b/src/header/spawn/cbindgen.toml
@@ -0,0 +1,15 @@
+sys_includes = ["stddef.h", "sys/types.h", "sched.h", "signal.h"]
+include_guard = "_RELIBC_SPAWN_H"
+language = "C"
+style = "Type"
+no_includes = true
+cpp_compat = true
+
+[export]
+include = [
+  "posix_spawnattr_t",
+  "posix_spawn_file_actions_t",
+]
+
+[enum]
+prefix_with_name = true
diff --git a/src/header/spawn/mod.rs b/src/header/spawn/mod.rs
new file mode 100644
index 0000000..84ce717
--- /dev/null
+++ b/src/header/spawn/mod.rs
@@ -0,0 +1,105 @@
+//! `spawn.h` implementation. See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/spawn.h.html>.
+
+use crate::{
+    error::{Errno, ResultExt},
+    header::{
+        errno::EINVAL,
+        unistd::{execve, fork, _exit},
+    },
+    platform::{self, types::{c_char, c_int, c_short, pid_t}},
+};
+
+pub const POSIX_SPAWN_RESETIDS: c_int = 0x01;
+pub const POSIX_SPAWN_SETPGROUP: c_int = 0x02;
+pub const POSIX_SPAWN_SETSCHEDPARAM: c_int = 0x04;
+pub const POSIX_SPAWN_SETSCHEDULER: c_int = 0x08;
+pub const POSIX_SPAWN_SETSIGDEF: c_int = 0x10;
+pub const POSIX_SPAWN_SETSIGMASK: c_int = 0x20;
+pub const POSIX_SPAWN_SETSID: c_int = 0x80;
+
+#[repr(C)]
+pub struct posix_spawn_file_actions_t {
+    _opaque: [u8; 128],
+}
+
+#[repr(C)]
+pub struct posix_spawnattr_t {
+    pub flags: c_short,
+    pub pgroup: pid_t,
+    _reserved: [u64; 8],
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn_file_actions_init(
+    file_actions: *mut posix_spawn_file_actions_t,
+) -> c_int {
+    if file_actions.is_null() {
+        return Err::<c_int, _>(Errno(EINVAL)).or_minus_one_errno();
+    }
+    unsafe { core::ptr::write_bytes(file_actions, 0, 1) };
+    0
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn_file_actions_destroy(
+    _file_actions: *mut posix_spawn_file_actions_t,
+) -> c_int { 0 }
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn_file_actions_addopen(
+    _file_actions: *mut posix_spawn_file_actions_t,
+    _fildes: c_int, _path: *const c_char, _oflag: c_int, _mode: c_int,
+) -> c_int { 0 }
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn_file_actions_addclose(
+    _file_actions: *mut posix_spawn_file_actions_t,
+    _fildes: c_int,
+) -> c_int { 0 }
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn_file_actions_adddup2(
+    _file_actions: *mut posix_spawn_file_actions_t,
+    _fildes: c_int, _newfildes: c_int,
+) -> c_int { 0 }
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawnattr_init(attr: *mut posix_spawnattr_t) -> c_int {
+    if attr.is_null() { return Err::<c_int, _>(Errno(EINVAL)).or_minus_one_errno(); }
+    unsafe { core::ptr::write_bytes(attr, 0, 1) };
+    0
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawnattr_destroy(_attr: *mut posix_spawnattr_t) -> c_int { 0 }
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawnp(
+    pid: *mut pid_t, file: *const c_char,
+    file_actions: *const posix_spawn_file_actions_t,
+    attrp: *const posix_spawnattr_t,
+    argv: *const *mut c_char, envp: *const *mut c_char,
+) -> c_int {
+    unsafe { posix_spawn(pid, file, file_actions, attrp, argv, envp) }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn posix_spawn(
+    pid: *mut pid_t, file: *const c_char,
+    _file_actions: *const posix_spawn_file_actions_t,
+    _attrp: *const posix_spawnattr_t,
+    argv: *const *mut c_char, envp: *const *mut c_char,
+) -> c_int {
+    if pid.is_null() || file.is_null() || argv.is_null() {
+        return EINVAL;
+    }
+    let child = unsafe { fork() };
+    if child < 0 { return platform::ERRNO.get(); }
+    if child == 0 {
+        unsafe { execve(file, argv, envp); }
+        _exit(127);
+    }
+    unsafe { *pid = child };
+    0
+}
+