The effects of acetylene self-collisions on alignment have been studied in detail. Strongly aligned samples of C2H2 were prepared in several rotational states of the 2(1) level by stimulated Raman pumping. Laser-induced fluorescence verified the initial degree of alignment and was used to follow its decrease via collisions. Measurements of the initially excited alignment agree well with theoretical calculations of that achievable by stimulated Raman pumping, and the decay can be well modeled by a simple kinetic scheme.