Background: Yoga may provide a strategy for healthy weight management in young adults. This study examined prevalence and characteristics of young adults’ yoga practice and associations with changes in body mass index. Methods: Surveys were completed by 1830 young adults (31.1 ± 1.6 y) participating in Project EAT-IV. Cross-sectional and 5-year longitudinal analyses were conducted stratified by initial weight status. Results: Two-thirds (66.5%) of nonoverweight women and 48.9% of overweight women reported ever doing yoga, while 27.2% of nonoverweight women and 16.4% of overweight women practiced regularly (≥30 min/wk). Fewer men practiced yoga. Among young adults practicing regularly (n = 294), differences were identified in intensity, type, and location of yoga practice across weight status. Young adults who were overweight and practiced yoga regularly showed a nonsignificant 5-year decrease in their body mass index (−0.60 kg/m2; P = .49), whereas those not practicing regularly had significant increases in their body mass index (+1.37 kg/m2; P < .01). Frequency of yoga was inversely associated with weight gain among both overweight and nonoverweight young adults practicing yoga regularly. Conclusions: Young adults of different body sizes practice yoga. Yoga was associated with less weight gain over time, particularly in overweight young adults. Practicing yoga on a regular basis may help with weight gain prevention.