We used data from Kenya Demographic and Health Surveys in 1993, 1998, and 2003 to examine 10-year trends in primary and secondary abstinence among never-married youth aged 15-24 and to explore the role of HIV prevention knowledge, schooling, and contextual factors in affecting their abstinence behaviors. Our analysis shows that both primary and secondary abstinence levels have risen in the past 10 years, with the abstinence levels higher among females than among males. Logistic regression models indicate that knowledge that abstinence can prevent HIV infection was positively associated with the likelihood of practicing abstinence. However, knowledge that condom use can prevent HIV infection was associated with lower abstinence practice. In-school youth were more likely to abstain from sex than those working. Effects of the contextual variables were only significant on the likelihood of primary abstinence among female youth. These findings suggest abstinence programs needed to be gender sensitive and culturally appropriate.