Puerto Rican children are more likely to have asthma than children in any other racial/ethnic group in the United States, yet little research has examined the factors contributing to childhood asthma among Puerto Ricans. Using data from a representative sample of mainland Puerto Rican children, the present study investigates the relationship between preterm birth and early-childhood asthma (i.e., in the first years of life). The roles of other risk factors (i.e., socioeconomic and demographic characteristics, environmental conditions, and maternal health behavior) in the development of asthma in early childhood also are considered. The analysis reveals a relatively high rate of asthma for preterm children as well as differences between term and preterm children in the risk factors for early-childhood asthma. Measures of socioeconomic status and the cleanliness of the home environment are related to asthma for term, but not preterm, children; in contrast, demographic characteristics and maternal health behavior are important risk factors for asthma among preterm children.