I'm working on a Core Data app, following the examples I'm seeing on the web. This is my last major stumbling block to a successful working application... I have an NSArrayController called Fish that contains a bunch of different fish. And I have another NSArrayController called Aquarium that contains a bunch of different aquariums. I want to be able to specify in which aquarium a particular fish lives. I want to do this by having a list of all my aquariums in the right column of an NSTableView, and NSButtonCells (checkboxes) in the left column. So when I click on a particular fish in NSTableView #1, I can see which aquarium is checked in NSTableView #2. See my post further down for a visual example. My xcdatamodel currently looks like: Fish <---->> Aquariums. P.S. Is there a way to do this exclusively in Interface Builder? Or is there a better way to do this altogether? Edit: I will send $40 via Paypal to the first person who can walk me through this and help me get it working. The image below is what I'm talking about. I want to make which items are checked in Table 2 depend on the selection in Table 1, but the contents of Table 2 (aside from the checkboxes) should be the same as Table 3. I have been going by the tutorial on this page: http://www.cocoadevcentral.com/articles/000085.php PM me! Edit: Bounty increased to $40.