This book reports on a study which aimed to examine two groups of healthy older Dutch-English bilingual migrants in a New Zealand setting to see if they were showing signs of L2 attrition with accompanying L1 reversion post-retirement. It also aimed to identify possible factors which might play a role in the incidence of any L2 attrition and concomitant L1 reversion. The research design involved an analysis of sociolinguistic life, using questionnaires. These included self-assessments of L1 and L2 proficiency at three key times: on arrival in New Zealand, at time of ultimate attainment and post-retirement. An analysis of assessments of respondents'' L1 and L2 proficiency pre- and post-retirement, completed by interviewees'' adult children moderated respondents'' self-reports. The design also included a linguistis analysis of elicited free speech. Data focused on key indicators of age, gender, social class, prior education, occupation and predominant linguistic environment pre- and post-retirement. Free speech was examined for code-switching, response latency and L1 structure in respondents'' spoken L2. Case studies are also presented.