Almost 300 non-migrant, migrant, return migrant, and circulatory migrant high school students participated in a study of the relationship of the level of adjustment to mainstream Puerto Rican society and the frequency of migration. No direct relationship between reading achievement and physical adjustment was found. However, as the level of cultural adjustment increased, evidence of physical adjustment became more noticeable. A relationship was also discovered between reading achievement in Spanish and school adjustment, but none between reading achievement and social adjustment. Return migrant students were found not to have developed reading skills in Spanish at the same rate as those who never migrated. Differences between nonmigrants and circulatory migrants in reading achievement indicated that mobility greatly impaired the acquisition of second language reading skills. There were no differences between the groups in physical adjustment. A performance of the Stepwise Multiple Regression Analysis suggested that the best predictor of reading achievement was school adjustment. A negative relationship between physical adjustment and reading achievement suggested that achievement will increase as soon as physical adjustment occurs. (RDN)