This study examined young women's attempts to control reproduction through contraception and fertility protection or promotion in rural Tanzania. It drew on participant observation in nine villages, group discussions and interviews in three others, and 16 health facility simulated patient visits from 1999-2002. Fertility was highly valued, but out-of-wedlock pregnancies were stigmatized. Many girls used traditional contraception, such as wearing charms or drinking ash solutions. Young single mothers sometimes used modern contraception, including Depo Provera, because injections were accessible, private, and infrequent. However, use was ambivalent and inconsistent for fear of side effects, such as infertility (hormonal contraceptives) and reduced male pleasure (condoms). Newly married women tried to conceive immediately. Traditional treatments were used for infertility, miscarriage, or difficult deliveries. These were attributed to physical causes (sexually transmitted infections; contraception; abortion) and/or supernatural causes (God's will; witchcraft; ancestral punishment). Improved reproductive health education and services are greatly needed. The potential of condoms to protect future fertility should be emphasised.