The purpose of a housing adaptation is to enhance daily activities and to improve housing accessibility and usability by removing physical barriers in the home. The aim of this study was to investigate longitudinal changes in housing accessibility among clients receiving grants for housing adaptations. Baseline assessments were administered one month before the housing adaptation, with the first follow-up after two to three months, and the second follow-up after eight to nine months. The Housing Enabler and the Usability in My Home instruments were used to collect data from 131 consecutively enrolled clients living in general housing. Accessibility and usability improved significantly, the number of physical environmental barriers decreased and dependence on mobility devices increased, but at different times along the process. The results indicate the complexity of the housing adaptation process and the need to consider person-environment interactions over time. The methodology seems useful for quality development of assessment, intervention and evaluation processes in housing adaptations performed by occupational therapists.