Polymer-assisted deposition is a chemical solution route to high quality thin films. In this process, the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of crack-free and uniform films after thermal treatment. We review our recent effort to epitaxially grow metal-nitride thin films, such as hexagonal GaN, cubic TiN, AlN, NbN, and VN, mixed-nitride $Ti_{1-x}Al_xN$, ternary nitrides tetragonal $SrTiN_2$, $BaZrN_2$, and $BaHfN_2$, hexagonal $FeMoN_2$, and nanocomposite TiN-$BaZrN_2$.