Studies continue to report minimal (or negligible) institutional rehabilitation outcomes among the prison inmates serving various offences; particularly in developing countries. Reports indicate that the rate of recidivism and re-conviction is even more acute in some of the regions, particularly Sub-Sahara Africa. The study examined rehabilitation outcomes of the prison inmates and the role of the socio-economic characteristics on those rehabilitation outcomes. The study employed Life course perspective and socio-economic vulnerability theory to identify phases of life typically associated with socio-economic vulnerabilities. The specific objectives of the study were 1) to identify rehabilitation outcomes of the prison inmates; 2) to examine their socio-economic characteristics; and 3) to examine the role (influence) of those characteristics on rehabilitation outcomes in respect to prerelease readiness to lawful livelihoods and community environment. The study was carried-out within three (3) selected correction institutions in Nairobi, Kenya, through a survey design. A sample of 286 subjects was used. Data was collected through key informants, focused group discussions (FGDs) and survey questionnaire. Results indicated that rehabilitation outcomes were substantially limited or inadequate in most of the indicators including compliance to institutional rules, participation of inmates in the design of their respective rehabilitation plans, access to apprenticeship, access to productive activities, exposure to employment experience, opportunity to engage with prospective employers, and opportunity to visit the family with a view to maintain support. Study results indicated that characteristics of the inmates had substantial influence on the rehabilitation outcomes. The study concluded that life course and socio-economic characteristics of the inmates needed to be taken into account in the institutional rehabilitation for the purposes of sustained rehabilitation outcomes.