Abstract
Abstract Doctoral education plays a pivotal role in strengthening research capacity, innovation, and socioeconomic development in Sub-Saharan Africa. Despite substantial growth in doctoral enrolment across the region, many higher education systems continue to face institutional and structural challenges that undermine student retention and timely completion. Existing evidence remains fragmented, with limited comparative understanding of the factors shaping doctoral trajectories across different national contexts. This study examined doctoral enrolment, retention, and completion in Kenya, Rwanda, and Ethiopia using a comparative explanatory sequential mixed-methods design. Quantitative data were collected from 154 doctoral students enrolled in structured doctoral training programmes across the three countries, complemented by 27 key informant interviews with doctoral supervisors, university administrators, and higher education stakeholders. Quantitative data were analysed using descriptive comparative statistics, while qualitative data were analysed thematically to explain the observed cross-country patterns. The findings reveal marked variation in doctoral progression across the three higher education systems. Rwanda exhibited comparatively stronger institutional support, reflected in more structured doctoral programmes, consistent supervisory engagement, regular academic progress monitoring, and accessible student support services. In contrast, respondents in Kenya and Ethiopia reported greater constraints associated with delayed research funding, inconsistent supervision, limited research infrastructure, weaker institutional support, and competing professional and family responsibilities. Female participation remained comparatively low across all three countries, highlighting persistent gender disparities in doctoral education. Overall, the study demonstrates that doctoral enrolment, retention, and completion are shaped by the interaction of institutional, socioeconomic, and psychosocial factors rather than by enrolment expansion alone. By providing comparative evidence across three Eastern African higher education systems, the study advances understanding of the systemic determinants of doctoral success and highlights the need for integrated doctoral ecosystems that align high-quality supervision, sustainable funding, research infrastructure, psychosocial support, and institutional governance to strengthen doctoral training and long-term research capacity in Sub-Saharan Africa.