The present invention provides improved devices for co-culture of cells. The devices include inserts having invertible wells that can be lowered into a well of any standard cell culture plate. A first population of cells can be cultured in the invertible wells of the inserts and a second population of cells can be cultured in the wells of a cell culture plate. Once the first population of cells attach to the invertible wells, the inserts are flipped over and placed into the wells of the cell culture plate to co-culture with the second population of cells.