This document was written to support the work of Migrant and Seasonal Head Start (MSHS) programs. The message provided is straightforward: we can meet the challenge of supporting first and second language development in preschool children. This paper is organized around four questions: (1) Can we facilitate children's acquisition of English without the loss of their first language? (2) How can we understand the how and when of developmental processes related to first and second language acquisition? (3) Does it matter how adults use English and children's home language when they talk to children? (4) When we continue development of the first language and facilitate English, what does it look like day-to-day? The paper reviews responses from the field, compares notes on the research literature, and presents both general guidelines and examples of specific practices that appear to be the most promising. [This report was produced by the Academy for Educational Development (AED) Center for Early Care and Education.]