The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration, a NSF Physics Frontiers Center, searches for gravitational waves (GWs) in pulsar timing data from Arecibo Observatory (AO) and the Green Bank Telescope (GBT). The Student Teams of Astrophysics Researchers (STARS) program engages undergraduates through training in key science areas of NANOGrav that contribute to GW detection — in particular, searching survey data for new pulsars and conducting remote timing observations with AO and the GBT. Weekly STARS telecons and student sessions at collaboration meetings train students in these skills, as well as in soft skills such as presenting, leadership, and networking with senior researchers. Students participate in research abroad through the International Research Experiences for Students (IRES) program. Students' pulsar discoveries are essential for GW detection, as the signal-to-noise of the GW background amplitude scales linearly with the number of pulsars regularly timed. We also highlight our recent program to broaden participation in STARS beyond students at full-time, four-year colleges and universities.