This paper examines the concept of management of diversification at tertiary education level in view of the growth of national secondary education system which vested high scramble for tertiary education was made in relation to question of access and expansion. This paper examines management of diversification at tertiary education level as a means by which tertiary education prepares itself to cope with the challenges that result from mass enrolment of primary and secondary schools. It reviewed that, often, a straightforward relationship is presumed between the growth of students' body and the expansion of tertiary education levels and between the growth of students' numbers and the diversity of such within the concept of its carrying capacity. Quality and standard of tertiary education, irrelevance of curricula to community aspirations, employability of school graduates, the continued reduction of financial resources and growing accountability measures imposed by governments on tertiary education were identified among others as probable problems of diversification of tertiary education in Nigeria. The paper also explores probable solutions to problems of diversification in tertiary education levels in Nigeria. For best practice to be obtained in our tertiary education, the paper recommends that strict adherence to the provision of the tertiary education autonomy using the yardstick of global best practices; diversification of funding by attracting private sectors; updating and restructuring institutional curriculum to meet national and globalised market demands and setting up effective monitoring system should be put in place by educational stakeholders.