Singleton (applied linguistics, Trinity College, Dublin, Ireland) and Ryan (a speech and language therapists for community care in Area Seven of the Northern Area Health Board, Dublin, Ireland) review the empirical and theoretical literature on the impact of age on language acquisition. They explore the evidence related to speech milestones, a critical period for first language acquisition, and optimum ages for second language learning. They also outline the various explanations that have been offered for evidence of an age-related factor and consider educational issues related to language instruction at elementary school and adult levels. Annotation ©2004 Book News, Inc., Portland, OR (booknews.com)