Sustainable Development Goal number 4 aims at ensuring inclusivity and equitable quality education that promote lifelong learning opportunities for all. However, girls’ dropout rate in developing countries has become a contemporary issue. Kenya has adopted international legal instruments on equal and quality education for both boys and girls. But data obtained from the ministry of education indicates that girls’ drop-out rates in secondary schools are higher than boys’ drop-out rates. This paper therefore, examined the extent to which parental economic status, early marriages, and school environment influence girls’ drop-out rates in secondary schools. The study adopted a mixed method approach. The study findings might be significant to Kenya and Africa south of Sahara. Regression analysis showed that economic status, early marriages, and school environment influence girls’ drop-out rate by 46.6 percent. The study recommended that the Ministry of Education enhances a policy to redress girls’ drop-out rates in secondary schools.