A common explanation for the high fertility prevailing in sub-Saharan Africa (SSA) is a widespread desire for large families. This situation poses a challenge to population policy-makers in the continent. If the desired family size is high, then presumably family planning programs can only have a limited effect on fertility because these programs aim to assist women in achieving their reproductive goals. But this conclusion is based on the assumption that family planning programs do not affect the desired family size, which is questionable and is investigated here. This study examines the determinants of trends wanted and unwanted fertility in SSA using fixed-effects regressions of country-level data. The dependent variables include the total fertility rate, and its wanted and unwanted components. Explanatory variables include a family planning program score and four socioeconomic variables (women’s educational attainment, child mortality, GNI per capita, and percent urban). Data come from 103 DHS surveys in 25 countries in SSA with at least two DHS surveys between 1989 and 2019. Women’s education and family planning programs are found to be the dominant determinants of fertility decline and their effects operate by reducing both wanted and unwanted fertility. The effects of education are not surprising but the finding that family planning programs can reduce wanted fertility implies that their impact can be larger than conventional wisdom suggests. Indeed, in a few poor countries, the implementation of high-quality programs has been associated with substantial declines in wanted fertility (e.g., Ethiopia, Malawi, Rwanda). The mechanism through which this effect operates is unclear but likely involves media programs that diffuse knowledge about the benefits of smaller families.