A study investigated the relative effect of 45-minute and 90-minute daily instruction in English as a Second Language (ESL) on limited English proficient (LEP) first-graders' language and overall achievement. The subjects were two groups of pupils from different schools: (1) 13 pupils from 7 language backgrounds, receiving 45 minutes of instruction daily; and (2) 17 pupils representing 5 native languages, receiving 90 minutes of instruction. Data used for analysis included reading and language test scores, oral language proficiency test scores, and teacher-provided information on overall grades. Results indicate that the pupils in shorter ESL class, which was also smaller, made higher grades in the regular classroom than did the other group. The short-class group also had higher oral proficiency test scores, but not significantly higher reading and language test scores. It is concluded that class size and time may have some significant effect on regular classroom achievement and oral language achievement but not may not affect scores on standardized achievement tests. (MSE)