diff --git a/CHANGELOG.develop b/CHANGELOG.develop
index 42331b544..ab9350c0f 100644
--- a/CHANGELOG.develop
+++ b/CHANGELOG.develop
@@ -311,6 +311,7 @@ sane way, here is the complete list of changed key bindings
 - perl5 (thanks to Troy Hinckley, Jinseop Kim and Michael Rohleder)
 - perl6 (thanks to Bahtiar Gadimov and yuhan0)
 - prolog (thanks to Newres Al Haider)
+- reasonml (thanks to fredyr and Dave Aitken)
 - protobuf (thanks to Amol Mandhane)
 - restructuredtext (thanks to Wei-Wei Guo and Kalle Lindqvist)
 - semantic-web (thanks to Andreas Textor)
@@ -1596,7 +1597,7 @@ Other:
 - Added missing prefixes for =web-mode= and =css-mode= (thanks to Uroš Perišić)
 - Fixed ~TAB~ indenting in =web-mode= (thanks to Christopher Eames)
 - Added =lsp= support for =css-mode=, =less-css-mode=, and =scss-mode=
-- Added support for =prettier= formatter in HTML buffers 
+- Added support for =prettier= formatter in HTML buffers
 **** Hy
 - Added support for virtual envs (thanks to Danny Freeman)
 - Key bindings:
@@ -2224,6 +2225,19 @@ Other:
   - Use JSX header without breaking React (thanks to Jam Risser)
   - Fixed React imports when using web beautify. (thanks to Ismael)
   - Made layer depends on node and tern layers (thanks to Sylvain Benner)
+**** ReasonML
+- Key bindings:
+  - ~SPC m g g~ Jump to definition
+  - ~SPC m g G~ Jump to definition (other window)
+  - ~SPC m g b~ Jump back
+  - ~SPC m h t~ Show type
+  - ~SPC m h h~ Show docs
+  - ~SPC m r d~ Merlin destruct
+  - ~SPC m = =~ Refmt
+  - ~SPC m t r~ Toggle auto-refmt on save
+  - ~SPC m = m r~ Refmt: convert ml syntax to re syntax
+  - ~SPC m = r m~ Refmt: convert re syntax to ml syntax
+    (thanks to Fredrik Dyrkell and Dave Aitken)
 **** Ruby
 - Added support for =org-babel= (thanks to Muneeb Shaikh)
 - Highlight debugger keywords (thanks to Alexander Berezovsky and Eivind Fonn)
diff --git a/layers/+lang/reasonml/README.org b/layers/+lang/reasonml/README.org
new file mode 100644
index 000000000..e8f51897c
--- /dev/null
+++ b/layers/+lang/reasonml/README.org
@@ -0,0 +1,76 @@
+#+TITLE: ReasonML layer
+
+[[https://reasonml.github.io/img/reason.svg]]
+
+* Description
+
+Spacemacs layer for ReasonML, based around [[https://github.com/reasonml-editor/reason-mode][reason-mode]].
+
+** Features:
+  - Syntax highlighting / indentation
+  - Autocomplete (via =merlin=)
+  - Lint / error display (via =merlin=, and =flycheck= if =syntax-checking= layer is enabled)
+  - REPL via =rtop=
+  - Auto-formatting (via =refmt=)
+
+* Install
+
+To use this configuration layer, add it to your =~/.spacemacs=. You will need to
+add =reasonml= to the existing =dotspacemacs-configuration-layers= list in this
+file.
+
+This layer depends on the `ocaml` layer which should be installed automatically.
+
+** Merlin
+
+You'll need merlin (binaries =ocamlmerlin= and =ocamlmerlin-reason=) installed
+on your system and on your =PATH= for errors and auto-completion.
+
+If you're familiar with =opam= you can
+#+BEGIN_SRC sh
+  opam install merlin reason
+#+END_SRC
+to get =ocamlmerlin= and =ocamlmerlin-reason= on your current =opam= switch.
+
+** Refmt
+
+Similarly to Merlin, you'll need the =refmt= binary on your path.
+
+If you're familiar with =opam= you can
+#+BEGIN_SRC sh
+  opam install reason
+#+END_SRC
+to get =refmt= in your current =opam switch=.
+
+If your project depends on a specific version of =refmt=, you can set
+=refmt-command= (via =customize-mode= or =(setq refmt-command ..)=) to the path
+to a particular binary. You can also use the special values ='npm= or ='opam= to
+run =refmt= via =npx= or =opam exec=, which will keep you on the correct version
+for your current opam switch, or the project-local of =node_modules=.
+
+You can toggle =refmt= on save with =SPC m r t=. To permanently enable it, add the layer variable:
+#+BEGIN_SRC emacs-lisp
+  (reasonml :variables reason-auto-refmt t)
+#+END_SRC
+in your =dotspacemacs-configuration-layers=.
+
+* Key bindings
+
+The main keybindings, see =packages.el= for the main list.
+
+| Key binding   | Description                           |
+|---------------+---------------------------------------|
+| ~SPC m g g~   | Jump to definition                    |
+| ~SPC m g G~   | Jump to definition (other window)     |
+| ~SPC m g b~   | Jump back                             |
+| ~SPC m h t~   | Show type                             |
+| ~SPC m h h~   | Show docs                             |
+| ~SPC m r d~   | Merlin destruct                       |
+| ~SPC m = =~   | Refmt                                 |
+| ~SPC m t r~   | Toggle auto-refmt on save             |
+| ~SPC m = m r~ | Refmt: convert ml syntax to re syntax |
+| ~SPC m = r m~ | Refmt: convert re syntax to ml syntax |
+
+* Thanks
+
+Special thanks to [[https://github.com/fredyr/][fredyr]] who wrote the initial verison of this layer.
diff --git a/layers/+lang/reasonml/config.el b/layers/+lang/reasonml/config.el
new file mode 100644
index 000000000..c7730b4c0
--- /dev/null
+++ b/layers/+lang/reasonml/config.el
@@ -0,0 +1,13 @@
+;;; config.el --- reasonml layer configuration file for Spacemacs
+;;
+;; Copyright (c) 2012-2018 Sylvain Benner & Contributors
+;;
+;; Author: Dave Aitken <dave.aitken@gmail.com>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(defvar-local reason-auto-refmt nil
+  "Whether to automatcally run refmt on save in the current reason-mode buffer.")
diff --git a/layers/+lang/reasonml/funcs.el b/layers/+lang/reasonml/funcs.el
new file mode 100644
index 000000000..a9de2c1aa
--- /dev/null
+++ b/layers/+lang/reasonml/funcs.el
@@ -0,0 +1,28 @@
+;;; funcs.el --- reasonml layer functions file for Spacemacs
+;;
+;; Copyright (c) 2012-2018 Sylvain Benner & Contributors
+;;
+;; Author: Dave Aitken <dave.aitken@gmail.com>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(defun reason/rtop-prompt ()
+  "The rtop prompt function."
+  (let ((prompt (format "rtop[%d]> " utop-command-number)))
+    (add-text-properties 0 (length prompt) '(face utop-prompt) prompt)
+    prompt))
+
+(defun reason/refmt-re-to-ml ()
+  (interactive)
+  (if (use-region-p)
+      (apply-refmt (region-beginning) (region-end) "re" "ml")
+    (apply-refmt nil nil "re" "ml")))
+
+(defun reason/refmt-ml-to-re ()
+  (interactive)
+  (if (use-region-p)
+      (apply-refmt (region-beginning) (region-end) "ml" "re")
+    (apply-refmt nil nil "ml" "re")))
diff --git a/layers/+lang/reasonml/layers.el b/layers/+lang/reasonml/layers.el
new file mode 100644
index 000000000..b0a7b084f
--- /dev/null
+++ b/layers/+lang/reasonml/layers.el
@@ -0,0 +1,12 @@
+;;; layers.el --- reasonml layer layers file for Spacemacs
+;;
+;; Copyright (c) 2012-2018 Sylvain Benner & Contributors
+;;
+;; Author: Dave Aitken <dave.aitken@gmail.com>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(configuration-layer/declare-layer 'ocaml)
diff --git a/layers/+lang/reasonml/packages.el b/layers/+lang/reasonml/packages.el
new file mode 100644
index 000000000..f3cfab4f0
--- /dev/null
+++ b/layers/+lang/reasonml/packages.el
@@ -0,0 +1,150 @@
+;;; packages.el --- reasonml layer packages file for Spacemacs.
+;;
+;; Copyright (c) 2012-2016 Sylvain Benner & Contributors
+;;
+;; Author: Fredrik Dyrkell
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(defconst reasonml-packages
+  '(company
+    evil-matchit
+    flycheck
+    flycheck-ocaml
+    merlin
+    popwin
+    reason-mode
+    utop))
+
+(defun reasonml/post-init-company ()
+  (when (configuration-layer/package-usedp 'merlin)
+    (spacemacs|add-company-backends
+      :backends merlin-company-backend
+      :modes reason-mode)))
+
+(defun reasonml/post-init-evil-matchit ()
+  (evilmi-load-plugin-rules '(reason-mode) '(template simple html))
+  (add-hook 'reason-mode-hook 'turn-on-evil-matchit-mode))
+
+(defun flycheck-ocaml-reason-setup ()
+  (with-eval-after-load 'merlin
+    (setq merlin-error-after-save nil)
+
+    (flycheck-define-generic-checker 'reason-merlin
+      "A syntax checker for Reason using Merlin Mode.
+    See URL `https://github.com/the-lambda-church/merlin'."
+      :start #'flycheck-ocaml-merlin-start
+      :verify #'flycheck-verify-ocaml-merlin
+      :modes '(reason-mode)
+      :predicate (and merlin-mode
+                      ;; Don't check if Merlin's own checking is
+                      ;; enabled, to avoid duplicate overlays
+                      (not merlin-error-after-save)))
+
+    (interactive)
+    (add-to-list 'flycheck-checkers 'reason-merlin)))
+
+(defun reasonml/post-init-flycheck ()
+  (when (configuration-layer/layer-used-p 'syntax-checking)
+    (spacemacs/enable-flycheck 'reason-mode)))
+
+(defun reasonml/post-init-flycheck-ocaml ()
+  (when (configuration-layer/layer-used-p 'syntax-checking)
+    (flycheck-ocaml-reason-setup)))
+
+(defun reasonml/post-init-merlin ()
+  (use-package merlin
+    :defer t
+    :init
+    (progn
+      (setq merlin-completion-with-doc t)
+
+      (spacemacs/set-leader-keys-for-major-mode 'reason-mode
+        "cp" 'merlin-project-check
+        "cv" 'merlin-goto-project-file
+        "eC" 'merlin-error-check
+        "en" 'merlin-error-next
+        "eN" 'merlin-error-prev
+        "gb" 'merlin-pop-stack
+        "gg" 'merlin-locate
+        "gG" 'spacemacs/merlin-locate-other-window
+        "gl" 'merlin-locate-ident
+        "gi" 'merlin-switch-to-ml
+        "gI" 'merlin-switch-to-mli
+        "go" 'merlin-occurrences
+        "hh" 'merlin-document
+        "ht" 'merlin-type-enclosing
+        "hT" 'merlin-type-expr
+        "rd" 'merlin-destruct))))
+
+(defun reasonml/pre-init-popwin ()
+  (spacemacs|use-package-add-hook popwin
+    :post-config
+    (push '("*Refmt Errors*" :tail t :position bottom :noselect t)
+          popwin:special-display-config)))
+
+(defun reasonml/init-reason-mode ()
+  (use-package reason-mode
+    :defer t
+    :mode ("\\.rei?\\'" . reason-mode)
+    :init
+    (progn
+      (add-hook 'reason-mode-hook 'merlin-mode)
+      (add-hook 'reason-mode-hook 'utop-minor-mode)
+      (when (configuration-layer/layer-used-p 'syntax-checking)
+        (add-hook 'reason-mode-hook 'flycheck-mode))
+
+      (add-hook 'reason-mode-hook
+                (lambda ()
+                  (when reason-auto-refmt
+                    (add-hook 'before-save-hook 'refmt nil t))))
+
+      (spacemacs|add-toggle reason-auto-refmt
+        :documentation "Toggle automatic refmt on save."
+        :status reason-auto-refmt
+        :on (progn
+              (setq reason-auto-refmt t)
+              (add-hook 'before-save-hook 'refmt nil t))
+        :off (progn
+               (setq reason-auto-refmt nil)
+               (remove-hook 'before-save-hook 'refmt t))))
+
+    :config
+    (progn
+      (spacemacs/declare-prefix-for-mode 'reason-mode "mc" "compile")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "mt" "toggle")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "me" "errors/eval")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "mg" "goto")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "mh" "help/show")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "mr" "refactor")
+      (spacemacs/declare-prefix-for-mode 'reason-mode "m=" "refmt")
+
+      (spacemacs/set-leader-keys-for-major-mode 'reason-mode
+        "cr" 'refmt
+        "==" 'refmt
+        "tr" 'spacemacs/toggle-reason-auto-refmt
+        "=mr" 'reason/refmt-ml-to-re
+        "=rm" 'reason/refmt-re-to-ml))))
+
+(defun reasonml/pre-init-utop ()
+  (spacemacs|use-package-add-hook utop
+    :post-init
+    (add-hook
+     'reason-mode-hook
+     (lambda ()
+       (setq utop-command "rtop -emacs")
+       (setq utop-edit-command nil)
+       (setq utop-prompt 'reason/rtop-prompt)
+       (setq utop-initial-command "let myVar = \"Hello Reason!\";")
+       (setq utop-phrase-terminator ";")))
+    :post-config
+    (progn
+      (spacemacs/set-leader-keys-for-major-mode 'reason-mode
+        "er" 'utop-eval-region
+        "eb" 'utop-eval-buffer
+        "ee" 'utop-eval-phrase))))
+
+;;; packages.el ends here