Educational resources and facilities cost money. The government and families mostly cover these expenditures. Kenya has spent considerably in education to improve access and participation. Despite these attempts, many students enroll in secondary school in form one, but the numbers drop as they advance to form four. Some are unsuccessful in the four-year course. The study's main goal was to determine the effect of direct educational costs on the transition rates of students in public boarding secondary schools in Uasin Gishu County. This research employed a Convergent Parallel Mixed Methods Design. 34 principals and 3,917 parents were targeted. The sample includes all the 34 principals and 362 parents purposively and Yamane's Simplified formula-selected respectively. Proportional random sampling aided in the choice of parents. Interviews, questionnaires, and archive content analysis collected data. Thematic analysis helped interpret qualitative data while inferential and descriptive statistics interpreted quantitative data. The findings indicated that, in public boarding secondary schools, student transition is highly connected with direct educational expenses. Direct educational expenditures predict public boarding secondary school students’ grade to grade transition rate. They explain 81.8% of the variation with repairs, maintenance and improvement cost accounting for the highest (34.7%) and school meals was responsible for 0.1% of the variance. The study concluded that, direct costs of education affect students’ grade to grade transition. It recommends the government to: review and increase student capitation so as to cover boarding expenses, diversify funding sources to fully cushion the needy students and fully fund school projects and programmes in order to relieve parents/guardians of the cost burden and thus increase student participation in Public Boarding Secondary schools. Keywords: Direct costs of education, Boarding Expenses, Board of Management Salaries and Motivation Fees, Public Boarding secondary Schools, Student Capitation, Students’ Transition Rates