diff --git a/ZeroTier One.xcodeproj/project.pbxproj b/ZeroTier One.xcodeproj/project.pbxproj
index 2730b9873..4fb0a76e2 100644
--- a/ZeroTier One.xcodeproj/project.pbxproj	
+++ b/ZeroTier One.xcodeproj/project.pbxproj	
@@ -287,6 +287,7 @@
 				93326BE71CE7C816005CA2AC /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
 	};
diff --git a/ZeroTier One/JoinNetworkViewController.swift b/ZeroTier One/JoinNetworkViewController.swift
index d071ce912..0aaaf10f0 100644
--- a/ZeroTier One/JoinNetworkViewController.swift	
+++ b/ZeroTier One/JoinNetworkViewController.swift	
@@ -8,11 +8,77 @@
 
 import Cocoa
 
-class JoinNetworkViewController: NSViewController {
+extension String {
+    func contains(find: String) -> Bool {
+        return self.rangeOfString(find) != nil
+    }
+
+    func trunc(length: Int, trailing: String? = "...") -> String {
+        if self.characters.count > length {
+            return self.substringToIndex(self.startIndex.advancedBy(length)) + (trailing ?? "")
+        } else {
+            return self
+        }
+    }
+}
+
+class JoinNetworkViewController: NSViewController, NSComboBoxDelegate {
+
+    @IBOutlet var network: NSComboBox!
+    @IBOutlet var joinButton: NSButton!
 
     override func viewDidLoad() {
         super.viewDidLoad()
-        // Do view setup here.
+        network.setDelegate(self)
     }
-    
+
+    @IBAction func onJoinClicked(sender: AnyObject?) {
+        let networkId = UInt64(network.stringValue, radix: 16)
+
+        // TODO: Execute join network call
+
+        network.stringValue = ""
+    }
+
+
+    // NSComboBoxDelegate Methods
+
+    override func controlTextDidChange(obj: NSNotification) {
+        let cb = obj.object as! NSComboBox
+        let value = cb.stringValue
+
+
+        let allowedCharacters = "abcdefABCDEF0123456789"
+
+        var outValue = ""
+
+        for char in value.characters {
+            if !allowedCharacters.contains(String(char)) {
+                NSBeep()
+            }
+            else {
+                outValue += String(char)
+            }
+        }
+
+
+
+        if outValue.lengthOfBytesUsingEncoding(NSUTF8StringEncoding) == 16 {
+            joinButton.enabled = true
+        }
+        else {
+
+            if outValue.lengthOfBytesUsingEncoding(NSUTF8StringEncoding) > 16 {
+                outValue = outValue.trunc(16, trailing: "")
+                NSBeep()
+                joinButton.enabled = true
+            }
+            else {
+                joinButton.enabled = false
+            }
+        }
+
+        cb.stringValue = outValue
+    }
+    // end NSComboBoxDelegate Methods
 }
diff --git a/ZeroTier One/JoinNetworkViewController.xib b/ZeroTier One/JoinNetworkViewController.xib
index 7f3f13297..2de44c9df 100644
--- a/ZeroTier One/JoinNetworkViewController.xib	
+++ b/ZeroTier One/JoinNetworkViewController.xib	
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="10116" systemVersion="15E65" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="10116" systemVersion="15F34" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
     <dependencies>
         <deployment identifier="macosx"/>
         <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="10116"/>
@@ -7,14 +7,45 @@
     <objects>
         <customObject id="-2" userLabel="File's Owner" customClass="JoinNetworkViewController" customModule="ZeroTier_One" customModuleProvider="target">
             <connections>
+                <outlet property="joinButton" destination="BGy-vd-NQX" id="LGE-2G-7ND"/>
+                <outlet property="network" destination="BQy-d9-BNg" id="Yf7-BG-c84"/>
                 <outlet property="view" destination="Hz6-mo-xeY" id="0bl-1N-x8E"/>
             </connections>
         </customObject>
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
         <customObject id="-3" userLabel="Application" customClass="NSObject"/>
         <customView id="Hz6-mo-xeY">
-            <rect key="frame" x="0.0" y="0.0" width="480" height="272"/>
+            <rect key="frame" x="0.0" y="0.0" width="369" height="101"/>
             <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
+            <subviews>
+                <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="puT-Yk-CWC">
+                    <rect key="frame" x="18" y="61" width="107" height="17"/>
+                    <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Enter Network ID" id="oYH-gS-BX5">
+                        <font key="font" metaFont="system"/>
+                        <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                        <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
+                    </textFieldCell>
+                </textField>
+                <comboBox verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="BQy-d9-BNg">
+                    <rect key="frame" x="131" y="57" width="221" height="26"/>
+                    <comboBoxCell key="cell" scrollable="YES" lineBreakMode="clipping" selectable="YES" editable="YES" sendsActionOnEndEditing="YES" borderStyle="bezel" drawsBackground="YES" completes="NO" numberOfVisibleItems="5" id="n71-4S-AaI">
+                        <font key="font" metaFont="system"/>
+                        <color key="textColor" name="controlTextColor" catalog="System" colorSpace="catalog"/>
+                        <color key="backgroundColor" name="textBackgroundColor" catalog="System" colorSpace="catalog"/>
+                    </comboBoxCell>
+                </comboBox>
+                <button verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="BGy-vd-NQX">
+                    <rect key="frame" x="274" y="13" width="81" height="32"/>
+                    <buttonCell key="cell" type="push" title="Join" bezelStyle="rounded" alignment="center" enabled="NO" borderStyle="border" imageScaling="proportionallyDown" inset="2" id="6Rp-TA-XLl">
+                        <behavior key="behavior" pushIn="YES" lightByBackground="YES" lightByGray="YES"/>
+                        <font key="font" metaFont="system"/>
+                    </buttonCell>
+                    <connections>
+                        <action selector="onJoinClicked:" target="-2" id="kzC-GT-JKb"/>
+                    </connections>
+                </button>
+            </subviews>
+            <point key="canvasLocation" x="249.5" y="361.5"/>
         </customView>
     </objects>
 </document>