Abstract: Low transition rate of seminarians from Minor Seminary schools to Major Seminary schools for priestly formation has translated to an inadequacy of priests for serving the church and the society. This poses a challenge to the Catholic Church that depends entirely on ordained priests from the Major Seminaries to carry out its evangelical functions. Studies in secular institutions have shown that family-related factors had major influence on learners’ transition rates. However, little research has been done to examine the influence of such family-related factors on transition of seminarians in seminary schools. This study thus sought to investigate the influence of family factors on transition rates of seminarians from Minor to Major Seminaries in Kisumu Ecclesiastical Province, Kenya. It targeted all the five rectors and 1075 former seminarians of the period 2014-2018 in all the five Minor Seminaries in the Ecclesiastical Province of Kisumu. The study was guided by Vygotsky’s socio-cultural theory of development.