This study examined the prevalence and sources of masturbatory practice in a nationally representative sample from China completed in the year 2000, with analysis of sources focused on 2,828 urban respondents aged 20-59. In this subpopulation, 13% (95% CI, 10-18) of women and 35% (CI, 26-44) of men reported any masturbation in the preceding year. Prevalence for people in their 20s was higher, and closer to US and European levels, especially for men. Particularly for women, masturbation not only compensated for absent partners but also complemented the high sexual interests of a subset of participants. For both women and men, practicing masturbation appeared to be a two-step process. In the first step, events such as sexual contact in childhood, early puberty, and early sex were related to sexualization and the "gateway event" of adolescent masturbation. In the second step, other factors, such as liberal sexual values and sexual knowledge, further increased the current probability of masturbation. Overall, the results suggest that masturbation is readily adopted even at more modest levels of economic and social development, that masturbation is often more than simply compensatory behavior for regular partnered sex, that masturbatory patterns are heavily influenced by early sexualization, and that a complex model is needed to comprehend masturbatory practice, particularly for women.