Seaside resorts' fortunes have changed over the past half a century, and as a consequence many of the towns' physical environments and inhabitants have altered. Many grew in population size through in-migration, particularly as a result of retirement, which took over from the holiday industry as a process that changed the socio-economic and cultural structures of these places. Bexhill-onSea, East Sussex is among those seaside towns that have undergone such changes, fuelled by exogenous forces but also influenced by key agencies actions that have been a catalyst for altering the physical environment which encouraged the in-migration of middle-life people and the retired. This thesis analyses the effect of these changes and the role key agencies have had. In particular, it argues the changing nature of retirement in-migration of 'middlelifers' (aged 50-70), those approaching or entering retirement, has had a profound effect on the town. This thesis disputes conventional retirement migration theories identifying a new form of 'lifestyle-affirming' migration.Based on empirical findings from semi-structured interviews with key agencies and middle-lifers, as well as desktop research, the methodology adopts a Lamarckian conceptual and theoretical perspective of socio-economic and cultural evolution that focuses on the influence on socio-economic change of the physical environment, key agency actions and middle-life migration. The thesis evidences both Darwinian and Lamarckian perspectives on evolutionary socio-economic change are useful for understanding resorts but at a local level human agency is a key component able to influence the cultural 'circonstances' which allows for changes in the physical environment and adaptation of the socio-economic, cultural and human capital of the seaside town. In Bexhill-onSea the elected officials and resident community were agencies that influenced socio-economic change and evolution.The town attracted middle-life migrants based on their personal experiences elsewhere that they imprinted on the town and from images and labels that were attached such as 'Costa Geriatrica'. Their choice of destination was constructed on 'gut-feel' from fleeting visits and perceived images that appealed to those middle-lifers who felt they would 'fit-in' with likeminded people and the town's culture. They brought their previous habitus and life experiences into an environment that is stable, quiet, safe and unchanging and best suits their social class disposition. This 'lifestyle-affirming' migration and 'personality-fit' was a significant and key finding in the research arguing for a new conceptualisation of middle-lifer and retirement migration of wanting to 'live by the sea' in a town that reflects their 'personality' and habitus, thus revealing more complicated forms of retirement or semi-retirement mobility. As middlelifers influence the nature of migration to seaside towns the consequential impact could be significant and questions the robustness of current retirement migration typologi...