On average, infant mortality rates are lower in more industrialized nations, yet health and mortality worsened during early industrialization in some nations. This study examines the effects of growing manufacturing employment on infant mortality across 274 Indonesian districts from 1985 to 1995, a time of rapid industrialization. Compared with cross-national studies we have a larger sample size of regions, more consistent data definitions, and better checks for causality and specification. We can also explore the causal mechanisms underlying our correlations. Overall the results suggest manufacturing employment raised living standards, housing quality, and reduced cooking with wood and coal, which helped reduce infant mortality. At the same time, pollution from factories appears quite harmful to infants. The overall effect was slightly higher infant mortality in regions that experienced greater industrialization.