Manufacturing is intensive in the use of reproducible factors and exhibits greater technological dynamism than primary production. As such, its growth is central to long-run development in low-income countries. African countries are latecomers to industrialization, and barriers to manufacturing growth, including those that limit trade, have been slow to come down. What factors contribute most to increases in output and productivity growth in African manufacturing? Recent trade–industrial organization theory suggests that trade liberalization should raise average total factor productivity (TFP) among manufacturing firms (Melitz 2003). However, these predictions are conditional on maintained assumptions about the nature of industries, factor markets, and trade patterns that may not be appropriate in a developing-country setting. Manufacturing firms are heterogeneous, so the analysis demands disaggregated data. We use firm-level data from the World Bank’s Regional Program on Enterprise Development, covering Ghana, Kenya, Nigeria, and Tanzania for 1991–2003. Among other things, the data distinguish exports by destination (Africa and the rest of the world), which is important due to the spread of intra-African regional trade agreements (RTAs). Econometric results confirm well-known relationships, such as a positive association between export intensity and TFP, which implies that more productive firms are more likely to select in to exporting. However, we also find the destination of exports to be important. Many exporters have experienced declining TFP growth rates, which have occurred at different rates depending on the country and the export destination. The evidence for “learning by exporting” is thus mixed. These results add a new dimension to controversies over the development implications of trade liberalization and the promotion of intra-African RTAs.