This study applied the Dynamic Social Systems Model (DSSM) to the issue of HIV risk among the Maasai tribe of Tanzania, using data from a cross-sectional, cluster survey among 370 randomly selected participants from Ngorongoro and Siha Districts. A culturally appropriate survey instrument was developed to explore traditions reportedly coadunate with sexual partnership, including "wife sharing", fertility rituals, and various traditional dances. One dance, esoto, accounted for more than two thirds of participants’ lifetime sexual partners (n = 10.5). The DSSM, combining structural and systems theories, was applied to systematize complex multilevel factors regarding esoto practice. Participants reported multifaceted beliefs regarding esoto; a majority viewed the dance as exciting and essential, yet most men feared social stigma and three quarters of women had experienced physical punishment for nonattendance. In multivariate logistic regression, esoto attendance was predicted by female gender (adjusted odds ratio [AOR] = 4.67, 95% confidence interval [CI] = 1.6-13.2), higher positive beliefs regarding esoto (AOR = 2.84, 95% CI = 1.9-4.2), and Maasai life cycle events (AOR = 0.06, 95% CI = 0.01-0.47). The DSSM proved useful for characterizing esoto and for revealing feedback loops that maintain esoto, thus indicating avenues for future interventions.