This paper presents new data on personnel commitments to United Nations peacekeeping operations from 1990 to 2011. For every operation during this period, data on the number of deployed troops, police and military observers are coded at the monthly level. Additionally, the number of each personnel type contributed by every UN member state is recorded. These data offer opportunities for testing theories of peacekeeping and conflict processes and present research avenues for which data have hitherto not existed. Herein, I introduce the data and coding processes, present trends, illustrate prospects for research that could benefit from these data and provide an empirical application.