diff --git a/client/assets/styles/scss/modals/modals-forms.scss b/client/assets/styles/scss/modals/modals-forms.scss
index 6a94fd52c..c23f3ec24 100644
--- a/client/assets/styles/scss/modals/modals-forms.scss
+++ b/client/assets/styles/scss/modals/modals-forms.scss
@@ -157,6 +157,7 @@
     // max-width on buttons
     > .btn,
     .btn-wrapped {
+      @extend %btn-sm;
       display: block;
       font-size: 16px;
       max-width: 360px;
diff --git a/client/assets/styles/scss/views/views-new-service.scss b/client/assets/styles/scss/views/views-new-service.scss
index a475c86ca..1ba50d754 100644
--- a/client/assets/styles/scss/views/views-new-service.scss
+++ b/client/assets/styles/scss/views/views-new-service.scss
@@ -44,6 +44,19 @@
     }
   }
 
+  // for branch selector
+  .btn-wrapped {
+    @extend %btn-md;
+    display: flex;
+    flex: 1 1 auto;
+    justify-content: space-between;
+    padding-left: 8px;
+
+    .icons-branch {
+      top: 9px;
+    }
+  }
+
   // for the nested compose test file
   .well > .label {
     margin-bottom: 0;
diff --git a/client/directives/components/fancySelectors/branchSelector/branchSelectorView.jade b/client/directives/components/fancySelectors/branchSelector/branchSelectorView.jade
index d4d9bbc7b..0a914b421 100644
--- a/client/directives/components/fancySelectors/branchSelector/branchSelectorView.jade
+++ b/client/directives/components/fancySelectors/branchSelector/branchSelectorView.jade
@@ -1,4 +1,4 @@
-fancy-select.btn-sm.white.btn-wrapped(
+fancy-select.white.btn-wrapped(
   ng-disabled = "branchFetching || !state.repo.branches.models.length"
   ng-required = "true"
   on-update = "onBranchChange"
diff --git a/client/directives/components/mirrorDockerfile/addDockerfileDirective.js b/client/directives/components/mirrorDockerfile/addDockerfileDirective.js
index 669073f24..0f5069f64 100644
--- a/client/directives/components/mirrorDockerfile/addDockerfileDirective.js
+++ b/client/directives/components/mirrorDockerfile/addDockerfileDirective.js
@@ -46,13 +46,21 @@ function addDockerfile(
         MDC.loadDefaultDockerfile($scope.fullRepo, $scope.branchName, path, $scope.fileType);
       }
 
-      fetchRepoDockerfile($scope.fullRepo, $scope.branchName, path)
-        .then(doesDockerfileExist)
-        .then(function (file) {
-          if (file) {
-            $scope.newDockerfile = $scope.fileName;
-          }
-        });
+
+      function populateNewDockerfile () {
+        return fetchRepoDockerfile($scope.fullRepo, $scope.branchName, path)
+          .then(doesDockerfileExist)
+          .then(function (file) {
+            if (file) {
+              $scope.newDockerfile = $scope.fileName;
+            } else {
+              // Account for files not found
+              $scope.newDockerfile = undefined;
+            }
+          });
+      }
+      $scope.$watch('branchName', populateNewDockerfile);
+      populateNewDockerfile();
 
       $scope.$on('dockerfileExistsValidator', function ($event, path, fileType, dockerfile) {
         if (fileType === 'Dockerfile') {
@@ -67,7 +75,7 @@ function addDockerfile(
           $scope.dockerfile = dockerfile;
           MDC.state.dockerfile = dockerfile;
           return;
-        } 
+        }
       });
 
       $scope.closeDockerFileInput = function () {
diff --git a/client/directives/components/mirrorDockerfile/mirrorDockerfileController.js b/client/directives/components/mirrorDockerfile/mirrorDockerfileController.js
index e3fad7b8b..8f7e02264 100644
--- a/client/directives/components/mirrorDockerfile/mirrorDockerfileController.js
+++ b/client/directives/components/mirrorDockerfile/mirrorDockerfileController.js
@@ -32,31 +32,6 @@ function MirrorDockerfileController(
   MDC.branchName = MDC.branchName || keypather.get(MDC.repo, 'attrs.default_branch');
   MDC.state.configurationMethod = null;
 
-  MDC.fetchRepoDockerfiles = function () {
-    return fetchRepoDockerfiles(MDC.getFullRepo(), MDC.branchName, MDC.newDockerfilePaths)
-      .then(function (dockerfiles) {
-        // remove any dead paths by replacing them with the results
-        MDC.newDockerfilePaths = dockerfiles.map(function (dockerfile) {
-          return dockerfile.path;
-        });
-        MDC.repo.dockerfiles = dockerfiles;
-        return dockerfiles;
-      })
-      .catch(errs.handler);
-  };
-
-  MDC.fetchRepoDockerComposeFiles = function () {
-    return fetchRepoDockerfiles(MDC.getFullRepo(), MDC.branchName, MDC.newDockerComposeFilePaths)
-      .then(function (dockerfiles) {
-        MDC.newDockerComposeFilePaths = dockerfiles.map(function (dockerfile) {
-          return dockerfile.path;
-        });
-        MDC.repo.dockerComposeFiles = dockerfiles;
-        return dockerfiles;
-      })
-      .catch(errs.handler);
-  };
-
   MDC.loadDefaultDockerfile = function  (repo, branchName, filePath, fileType) {
     return fetchRepoDockerfile(repo, branchName, filePath)
       .then(doesDockerfileExist)
diff --git a/client/directives/components/newContainer/forms/configureNewServiceView.jade b/client/directives/components/newContainer/forms/configureNewServiceView.jade
index 99b1a128e..d9f55e2fa 100644
--- a/client/directives/components/newContainer/forms/configureNewServiceView.jade
+++ b/client/directives/components/newContainer/forms/configureNewServiceView.jade
@@ -51,11 +51,17 @@ section.grid-block.vertical.modal-body(
     )
 
     //- form for naming the environment
-    form.grid-block.vertical.label(
+    form.grid-block.vertical.label.label-name(
       name = "NCC.nameForm"
       ng-include = "'nameNewServiceView'"
     )
 
+    //- default branch selector
+    label.grid-block.vertical.label(
+      ng-if = "NCC.state.dockerFileTab === 'compose' && $root.featureFlags.composeDefaultBranch"
+      ng-include = "'defaultBranchView'"
+    )
+
     .grid-block.vertical.views-kubernetes-setup(
       ng-if = "NCC.state.dockerFileTab === 'kubernetes'"
       ng-include = "'kubernetesSetupView'"
@@ -72,7 +78,7 @@ section.grid-block.vertical.modal-body(
 
     //- form for dockerfile setup
     .grid-block.vertical.label.views-dockerfile-setup(
-      branch-name = "NCC.state.repo.attrs.default_branch"
+      branch-name = "NCC.state.branch.attrs.name"
       mirror-dockerfile
       name = "'newContainer'"
       ng-if = "NCC.state.dockerFileTab !== 'kubernetes'"
diff --git a/client/directives/components/newContainer/forms/defaultBranchView.jade b/client/directives/components/newContainer/forms/defaultBranchView.jade
new file mode 100644
index 000000000..e64d1a58b
--- /dev/null
+++ b/client/directives/components/newContainer/forms/defaultBranchView.jade
@@ -0,0 +1,8 @@
+.padding-xxs.small.label-sm Initial Branch
+.grid-block(
+  auto-update = "true"
+  branch-selector
+  loading-promises-target = "editServerModal"
+  state = "NCC.state"
+)
+small.padding-xxs.small Select the first branch you want to add.
diff --git a/client/directives/components/newContainer/newContainerController.js b/client/directives/components/newContainer/newContainerController.js
index 567915c45..47975f38f 100644
--- a/client/directives/components/newContainer/newContainerController.js
+++ b/client/directives/components/newContainer/newContainerController.js
@@ -332,7 +332,7 @@ function NewContainerController(
     if (NCC.state.dockerComposeFile && (!$rootScope.featureFlags.composeNewService || NCC.state.types.stage)) {
       return createNewCluster(
         NCC.state.repo.attrs.full_name,
-        NCC.state.repo.attrs.default_branch,
+        NCC.state.branch.attrs.name,
         NCC.state.dockerComposeFile.path,
         NCC.state.instanceName,
         currentOrg.github.attrs.id
@@ -348,7 +348,7 @@ function NewContainerController(
           var instanceName = NCC.state.instanceName + '-test';
           return createNewCluster(
             NCC.state.repo.attrs.full_name,
-            NCC.state.repo.attrs.default_branch,
+            NCC.state.branch.attrs.name,
             NCC.state.dockerComposeTestFile.path,
             instanceName,
             currentOrg.github.attrs.id,
@@ -363,7 +363,7 @@ function NewContainerController(
 
     return createNewCluster(
       NCC.state.repo.attrs.full_name,
-      NCC.state.repo.attrs.default_branch,
+      NCC.state.branch.attrs.name,
       NCC.state.dockerComposeTestFile.path,
       NCC.state.instanceName,
       currentOrg.github.attrs.id,
@@ -383,17 +383,33 @@ function NewContainerController(
   };
 
   NCC.canCreateBuild = function () {
-    return  keypather.get(NCC, 'state.instanceName.length') && !keypather.get(NCC, 'nameForm.$invalid') &&
-            !$rootScope.isLoading.newContainerSingleRepo && !$rootScope.isLoading.creatingDockerCompose && (NCC.state.templateSource ||
-            !$scope.$root.featureFlags.composeNewService || NCC.validateDockerComposeBuild());
+    var hasInstances = keypather.get(NCC, 'state.instanceName.length');
+    var isLoading = $rootScope.isLoading.newContainerSingleRepo || $rootScope.isLoading.creatingDockerCompose;
+    var isFormValid = !keypather.get(NCC, 'nameForm.$invalid');
+    var isTemplate = NCC.state.templateSource;
+    var isValidCompose = !$scope.$root.featureFlags.composeNewService || NCC.validateDockerComposeBuild();
+    return hasInstances &&
+           isFormValid &&
+           !isLoading &&
+           (isTemplate || isValidCompose);
   };
 
   NCC.validateDockerComposeBuild = function () {
-    return ((NCC.state.configurationMethod === 'new' || NCC.state.configurationMethod === 'blankDockerfile') ||
-            (NCC.state.configurationMethod === 'dockerfile' && NCC.state.dockerfile) ||
-            (NCC.state.configurationMethod === 'dockerComposeFile' &&
-            ((NCC.state.types.test ? NCC.state.dockerComposeTestFile && NCC.state.testReporter : NCC.state.types.stage) &&
-            (NCC.state.types.stage ? NCC.state.dockerComposeFile : NCC.state.types.test))));
+    var isNewBlankDockerfile = ['new', 'blankDockerfile'].includes(NCC.state.configurationMethod);
+    var isValidDockerfile = NCC.state.configurationMethod === 'dockerfile' && NCC.state.dockerfile;
+    var isValidComposeFile = false;
+    if (NCC.state.configurationMethod === 'dockerComposeFile') {
+      var isValidTestCompose = true, isValidStagingCompose = true;
+      var hasTestOrStaging = NCC.state.types.test || NCC.state.types.stage;
+      if (NCC.state.types.test) {
+        isValidTestCompose = NCC.state.dockerComposeTestFile && NCC.state.testReporter;
+      }
+      if (NCC.state.types.stage) {
+        isValidStagingCompose = NCC.state.dockerComposeFile;
+      }
+      isValidComposeFile = hasTestOrStaging && isValidTestCompose && isValidStagingCompose;
+    }
+    return isNewBlankDockerfile || isValidDockerfile || isValidComposeFile;
   };
 
   NCC.isSaving = function () {
diff --git a/client/services/featureFlagService.js b/client/services/featureFlagService.js
index 17d618fc9..e883ec04f 100644
--- a/client/services/featureFlagService.js
+++ b/client/services/featureFlagService.js
@@ -14,6 +14,7 @@ function featureFlags(
     autoIsolationSetup: false,
     backup: false,
     cardStatus: false,
+    composeDefaultBranch: false,
     composeEditing: false,
     composeInstance: true,
     composeNav: true,