The fortunate conjunction of a large skeletal sample (n=576) and reliable burial records (n=1,564) for St. Thomas' Anglican Church cemetery (1821-1874) makes it possible to make inferences about patterns of infant death in 19th-century Belleville, Ontario. Analysis of both sets of data indicates that males and females were equally likely to die during infancy and that environmental factors played an important role in Belleville's mortality profile. The parish records reveal elevated risks of infant death in the summer, probably from the weanling diarrhea complex, owing to unsanitary conditions and the presence of acute infectious diseases in the town. The importance of acute causes is supported by patterns of skeletal growth and development that show that St. Thomas' infants were developmentally similar to modern North American children. The study also suggests an excavation bias in the skeletal sample, with an over-representation of burials from 1840 onward.