This study stems from the observation that lesbianism is fast creeping into Girls’ secondary schools in Nigeria. Using the ex-post facto research design, the study examined the influence of self-concept (moral and academic) on the acceptance of lesbianism tendency among 218 senior secondary school girls in Ovwie Local Government Area (LGA) of Delta State, Nigeria with a population of 2,112 senior secondary school girls. The respondents were randomly selected. The three research hypotheses formulated to guide this study were tested at a 0.05 level of significance. The instrument for data collection was the Self-concept and Acceptance of Lesbianism Tendency Questionnaire (SALTQ). The data were analyzed with the population and independent t-tests as the statistical tools. The results showed that the level of lesbianism tendency among senior secondary school girls in the study area was significantly high while a significant influence of moral and academic self-concepts on acceptance of lesbianism tendency was found to exist among the girls. Based on the findings, it was recommended that efforts should be made by the stakeholders of education to reduce the level of lesbianism among the senior secondary school girls by instituting programmes that sensitize them on the need to develop proper self-concept, the word of God and motivational talks can be appropriately used to encourage the development of moral concepts among the students, and self-concept enhancement programmes should be introduced in schools to enhance academic self-concept.