This 5-year longitudinal study investigated the English language acquisition and development of students in pre-Kindergarten through Grade 1 at a U.S.-accredited international school. Of the 1,509 students tested, the overwhelming majority were nonnative English speakers. The data provide valuable insight into the rate of second language acquisition for students at each grade level, including information on twins and students with learning differences. A strong emotional factor affecting language learning was also revealed. In addition, the researcher reviewed speaking scores to determine any far-reaching future correlation with reading/literacy test scores at the kindergarten and fourth-grade levels. Information on interventions used in an effort to raise proficiency levels and the effects of native- versus nonnative-English-speaking teachers on language scores is also included.