diff --git a/spec/fixtures/packages/package-with-grammars/grammars/alittle.cson b/spec/fixtures/packages/package-with-grammars/grammars/alittle.cson
deleted file mode 100644
index c72bea137..000000000
--- a/spec/fixtures/packages/package-with-grammars/grammars/alittle.cson
+++ /dev/null
@@ -1,12 +0,0 @@
-'fileTypes': ['alittle']
-'name': 'Alittle'
-'scopeName': 'source.alittle'
-
-'patterns': [
-  {
-    'captures':
-      '0':
-        'name': 'keyword.alittle'
-    'match': 'alittle'
-  }
-]
diff --git a/spec/fixtures/packages/package-with-grammars/grammars/alot.cson b/spec/fixtures/packages/package-with-grammars/grammars/alot.cson
deleted file mode 100644
index c8999a942..000000000
--- a/spec/fixtures/packages/package-with-grammars/grammars/alot.cson
+++ /dev/null
@@ -1,12 +0,0 @@
-'fileTypes': ['alot', 'foobizbang']
-'name': 'Alot'
-'scopeName': 'source.alot'
-
-'patterns': [
-  {
-    'captures':
-      '0':
-        'name': 'keyword.alot'
-    'match': 'alot'
-  }
-]
diff --git a/spec/fixtures/packages/package-with-injection-selector/grammars/grammar.cson b/spec/fixtures/packages/package-with-injection-selector/grammars/grammar.cson
deleted file mode 100644
index 3cee5379e..000000000
--- a/spec/fixtures/packages/package-with-injection-selector/grammars/grammar.cson
+++ /dev/null
@@ -1,4 +0,0 @@
-'name': 'test'
-'scopeName': 'source.test'
-'injectionSelector': 'comment'
-'patterns': [{'include': 'source.sql'}]
diff --git a/spec/fixtures/packages/package-with-keymaps-manifest/package.cson b/spec/fixtures/packages/package-with-keymaps-manifest/package.cson
deleted file mode 100644
index e7bdccfa7..000000000
--- a/spec/fixtures/packages/package-with-keymaps-manifest/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-keymaps: ["keymap-2", "keymap-1"]
diff --git a/spec/fixtures/packages/package-with-keymaps-manifest/package.json b/spec/fixtures/packages/package-with-keymaps-manifest/package.json
new file mode 100644
index 000000000..e1a4d416c
--- /dev/null
+++ b/spec/fixtures/packages/package-with-keymaps-manifest/package.json
@@ -0,0 +1,3 @@
+{
+  "keymaps": ["keymap-2", "keymap-1"]
+}
diff --git a/spec/fixtures/packages/package-with-main/package.cson b/spec/fixtures/packages/package-with-main/package.cson
deleted file mode 100644
index a93a109c4..000000000
--- a/spec/fixtures/packages/package-with-main/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-'main': 'main-module.coffee'
\ No newline at end of file
diff --git a/spec/fixtures/packages/package-with-main/package.json b/spec/fixtures/packages/package-with-main/package.json
new file mode 100644
index 000000000..fc218060f
--- /dev/null
+++ b/spec/fixtures/packages/package-with-main/package.json
@@ -0,0 +1,3 @@
+{
+  "main": "main-module.coffee"
+}
diff --git a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.cson b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.cson
deleted file mode 100644
index f35a42726..000000000
--- a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.cson
+++ /dev/null
@@ -1,8 +0,0 @@
-'menu': [
-  { 'label': 'Last' }
-]
-
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 1', command: 'command-1'}
-  ]
diff --git a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.json b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.json
new file mode 100644
index 000000000..81d7e470d
--- /dev/null
+++ b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-1.json
@@ -0,0 +1,5 @@
+{
+  "menu": [
+    { "label": "Last" }
+  ]
+}
diff --git a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.cson b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.cson
deleted file mode 100644
index e67b879d1..000000000
--- a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.cson
+++ /dev/null
@@ -1,8 +0,0 @@
-'menu': [
-  { 'label': 'Second to Last' }
-]
-
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 2', command: 'command-2'}
-  ]
diff --git a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.json b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.json
new file mode 100644
index 000000000..fb0c58e50
--- /dev/null
+++ b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-2.json
@@ -0,0 +1,5 @@
+{
+  "menu": [
+    { "label": "Second to Last" }
+  ]
+}
diff --git a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-3.cson b/spec/fixtures/packages/package-with-menus-manifest/menus/menu-3.cson
deleted file mode 100644
index a93a864ab..000000000
--- a/spec/fixtures/packages/package-with-menus-manifest/menus/menu-3.cson
+++ /dev/null
@@ -1,4 +0,0 @@
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 3', command: 'command-3'}
-  ]
diff --git a/spec/fixtures/packages/package-with-menus-manifest/package.cson b/spec/fixtures/packages/package-with-menus-manifest/package.cson
deleted file mode 100644
index 1a3efbda3..000000000
--- a/spec/fixtures/packages/package-with-menus-manifest/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-menus: ["menu-2", "menu-1"]
diff --git a/spec/fixtures/packages/package-with-menus-manifest/package.json b/spec/fixtures/packages/package-with-menus-manifest/package.json
new file mode 100644
index 000000000..59bf836f1
--- /dev/null
+++ b/spec/fixtures/packages/package-with-menus-manifest/package.json
@@ -0,0 +1,3 @@
+{
+  "menus": ["menu-2", "menu-1"]
+}
diff --git a/spec/fixtures/packages/package-with-menus/menus/menu-1.cson b/spec/fixtures/packages/package-with-menus/menus/menu-1.cson
deleted file mode 100644
index 0c95f5972..000000000
--- a/spec/fixtures/packages/package-with-menus/menus/menu-1.cson
+++ /dev/null
@@ -1,8 +0,0 @@
-'menu': [
-  {'label': 'Second to Last'}
-]
-
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 1', command: 'command-1'}
-  ]
diff --git a/spec/fixtures/packages/package-with-menus/menus/menu-1.json b/spec/fixtures/packages/package-with-menus/menus/menu-1.json
new file mode 100644
index 000000000..81d7e470d
--- /dev/null
+++ b/spec/fixtures/packages/package-with-menus/menus/menu-1.json
@@ -0,0 +1,5 @@
+{
+  "menu": [
+    { "label": "Last" }
+  ]
+}
diff --git a/spec/fixtures/packages/package-with-menus/menus/menu-2.cson b/spec/fixtures/packages/package-with-menus/menus/menu-2.cson
deleted file mode 100644
index 46c3fb9ef..000000000
--- a/spec/fixtures/packages/package-with-menus/menus/menu-2.cson
+++ /dev/null
@@ -1,8 +0,0 @@
-'menu': [
-  { 'label': 'Last' }
-]
-
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 2', command: 'command-2'}
-  ]
diff --git a/spec/fixtures/packages/package-with-menus/menus/menu-2.json b/spec/fixtures/packages/package-with-menus/menus/menu-2.json
new file mode 100644
index 000000000..fb0c58e50
--- /dev/null
+++ b/spec/fixtures/packages/package-with-menus/menus/menu-2.json
@@ -0,0 +1,5 @@
+{
+  "menu": [
+    { "label": "Second to Last" }
+  ]
+}
diff --git a/spec/fixtures/packages/package-with-menus/menus/menu-3.cson b/spec/fixtures/packages/package-with-menus/menus/menu-3.cson
deleted file mode 100644
index 445028db6..000000000
--- a/spec/fixtures/packages/package-with-menus/menus/menu-3.cson
+++ /dev/null
@@ -1,8 +0,0 @@
-'menu': [
-  { 'label': 'Second to Last' }
-]
-
-'context-menu':
-  '.test-1': [
-    {label: 'Menu item 3', command: 'command-3'}
-  ]
diff --git a/spec/fixtures/packages/package-with-models/package.cson b/spec/fixtures/packages/package-with-models/package.cson
deleted file mode 100644
index a93a109c4..000000000
--- a/spec/fixtures/packages/package-with-models/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-'main': 'main-module.coffee'
\ No newline at end of file
diff --git a/spec/fixtures/packages/package-with-models/package.json b/spec/fixtures/packages/package-with-models/package.json
new file mode 100644
index 000000000..fc218060f
--- /dev/null
+++ b/spec/fixtures/packages/package-with-models/package.json
@@ -0,0 +1,3 @@
+{
+  "main": "main-module.coffee"
+}
diff --git a/spec/fixtures/packages/package-with-serialize-error/package.cson b/spec/fixtures/packages/package-with-serialize-error/package.cson
deleted file mode 100644
index 300ce2fc0..000000000
--- a/spec/fixtures/packages/package-with-serialize-error/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-'main': 'index.coffee'
diff --git a/spec/fixtures/packages/package-with-serialize-error/package.json b/spec/fixtures/packages/package-with-serialize-error/package.json
new file mode 100644
index 000000000..02503ebe4
--- /dev/null
+++ b/spec/fixtures/packages/package-with-serialize-error/package.json
@@ -0,0 +1,3 @@
+{
+  "main": "index.coffee"
+}
diff --git a/spec/fixtures/packages/package-with-settings/settings/omg.cson b/spec/fixtures/packages/package-with-settings/settings/omg.cson
deleted file mode 100644
index 4a3037963..000000000
--- a/spec/fixtures/packages/package-with-settings/settings/omg.cson
+++ /dev/null
@@ -1,3 +0,0 @@
-'.source.omg':
-  'editor':
-    'increaseIndentPattern': '^a'
diff --git a/spec/fixtures/packages/package-with-style-sheets-manifest/package.cson b/spec/fixtures/packages/package-with-style-sheets-manifest/package.cson
deleted file mode 100644
index 07c6082e5..000000000
--- a/spec/fixtures/packages/package-with-style-sheets-manifest/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-styleSheets: ['2', '1']
diff --git a/spec/fixtures/packages/package-with-style-sheets-manifest/package.json b/spec/fixtures/packages/package-with-style-sheets-manifest/package.json
new file mode 100644
index 000000000..89d283d36
--- /dev/null
+++ b/spec/fixtures/packages/package-with-style-sheets-manifest/package.json
@@ -0,0 +1,3 @@
+{
+  "styleSheets": ["2", "1"]
+}
diff --git a/spec/fixtures/packages/package-with-stylesheets-manifest/package.cson b/spec/fixtures/packages/package-with-stylesheets-manifest/package.cson
deleted file mode 100644
index 07c6082e5..000000000
--- a/spec/fixtures/packages/package-with-stylesheets-manifest/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-styleSheets: ['2', '1']
diff --git a/spec/fixtures/packages/package-with-stylesheets-manifest/package.json b/spec/fixtures/packages/package-with-stylesheets-manifest/package.json
new file mode 100644
index 000000000..89d283d36
--- /dev/null
+++ b/spec/fixtures/packages/package-with-stylesheets-manifest/package.json
@@ -0,0 +1,3 @@
+{
+  "styleSheets": ["2", "1"]
+}
diff --git a/spec/fixtures/packages/package-without-module/package.cson b/spec/fixtures/packages/package-without-module/package.cson
deleted file mode 100644
index c6e451934..000000000
--- a/spec/fixtures/packages/package-without-module/package.cson
+++ /dev/null
@@ -1 +0,0 @@
-"name": "perfect"
diff --git a/spec/fixtures/packages/package-without-module/package.json b/spec/fixtures/packages/package-without-module/package.json
new file mode 100644
index 000000000..522074741
--- /dev/null
+++ b/spec/fixtures/packages/package-without-module/package.json
@@ -0,0 +1,3 @@
+{
+  "name": "perfect"
+}
diff --git a/spec/package-manager-spec.coffee b/spec/package-manager-spec.coffee
index be35380d6..3438edfb8 100644
--- a/spec/package-manager-spec.coffee
+++ b/spec/package-manager-spec.coffee
@@ -267,8 +267,8 @@ describe "PackageManager", ->
 
           runs ->
             expect(NylasEnv.menu.template.length).toBe 2
-            expect(NylasEnv.menu.template[0].label).toBe "Second to Last"
-            expect(NylasEnv.menu.template[1].label).toBe "Last"
+            expect(NylasEnv.menu.template[1].label).toBe "Second to Last"
+            expect(NylasEnv.menu.template[0].label).toBe "Last"
 
       describe "when the metadata contains a 'menus' manifest", ->
         it "loads only the menus specified by the manifest, in the specified order", ->
diff --git a/src/package.coffee b/src/package.coffee
index 74e265356..fc94d4f94 100644
--- a/src/package.coffee
+++ b/src/package.coffee
@@ -2,7 +2,6 @@ path = require 'path'
 
 _ = require 'underscore'
 async = require 'async'
-CSON = require 'season'
 fs = require 'fs-plus'
 EmitterMixin = require('emissary').Emitter
 {Emitter, CompositeDisposable} = require 'event-kit'
@@ -37,9 +36,10 @@ class Package
     if @isBundledPackagePath(packagePath)
       metadata = packagesCache[packageName]?.metadata
     unless metadata?
-      if metadataPath = CSON.resolve(path.join(packagePath, 'package'))
+      metadataPath = fs.resolve(path.join(packagePath, 'package.json'))
+      if fs.existsSync(metadataPath)
         try
-          metadata = CSON.readFileSync(metadataPath)
+          metadata = JSON.parse(fs.readFileSync(metadataPath))
         catch error
           throw error unless ignoreErrors
     metadata ?= {}
@@ -239,9 +239,9 @@ class Package
       if @bundledPackage and packagesCache[@name]?
         @menus = (["#{NylasEnv.packages.resourcePath}#{path.sep}#{menuPath}", menuObject] for menuPath, menuObject of packagesCache[@name].menus)
       else
-        @menus = @getMenuPaths().map (menuPath) -> [menuPath, CSON.readFileSync(menuPath) ? {}]
+        @menus = @getMenuPaths().map (menuPath) -> [menuPath, JSON.parse(fs.readFileSync(menuPath)) ? {}]
     catch e
-      console.error "Error reading keymaps for package '#{@name}': #{e.message}", e.stack
+      console.error "Error reading menus for package '#{@name}': #{e.message}", e.stack
 
   getKeymapPaths: ->
     keymapsDirPath = path.join(@path, 'keymaps')
@@ -253,9 +253,9 @@ class Package
   getMenuPaths: ->
     menusDirPath = path.join(@path, 'menus')
     if @metadata.menus
-      @metadata.menus.map (name) -> fs.resolve(menusDirPath, name, ['json', 'cson', ''])
+      @metadata.menus.map (name) -> fs.resolve(menusDirPath, name, ['json', ''])
     else
-      fs.listSync(menusDirPath, ['cson', 'json'])
+      fs.listSync(menusDirPath, ['json'])
 
   loadStylesheets: ->
     @stylesheets = @getStylesheetPaths().map (stylesheetPath) ->