This paper discusses the stage of second language acquisition known as attrition and what learners and teachers can do to prevent attrition and promote retention. Attrition is the stage at which a learner's attained proficiency declines due to a reduction of contact with the second language, whether from lack of contact with other speakers of the language, cessation of language instruction, or a number of other factors. The paper briefly summarizes research on language attrition, then reviews a prototype program developed to encourage L2 retention for a specific learner population, and discusses a range of activities in which learners at large may engage to promote retention of their L2 knowledge, including both traditional and technology-mediated activities. The paper also suggests means by which language teachers may prepare their students for the possibility of attrition and help them develop skills for independent learning and engaging with language activities and resources that will facilitate language retention.