This paper is premised on the findings of a study that sought to investigate factors that influence the participation and retention of the boy-child in public secondary schools in Baringo County, Kenya. Specifically, the study aimed at evaluating the effects of socio-economic factors on boy-child participation and retention in public secondary schools in Baringo County. Principles of the education production function theory guided the study. The study adopted a pragmatic world view (mixed method approach) with a sample size of 573 comprising form three boys' students, teachers and Quality Assurance and Standards Officers from Baringo County. The researcher adopted stratification, simple random sampling and purposive strategies for setting up samples. Questionnaires, interview schedules and document analysis were used for data collection and data analyzed using SPSS (ver 20). The study established that there are socio-economic and school-related factors affecting participation and retention of boys. In particular, poverty, family size and number of siblings per household, child labour and desire for earnings, and educational attainment of parents determine boy participation and retention in public secondary schools in Baringo County. The paper concludes that financial constraints hinder the participation and retention of boys in public secondary schools in Baringo County due to the fact that the meagre resources that are available are channelled to catering for basic survival. The paper recommends that measures should be put in place to ensure that needy students receive financial aid towards achieving their educational goals.