Growing human capacities in STEM remain the most practicable way to solving present and future challenges. Improved test score, opportunities to learn, resources and facilities have been recommended in the literature to build capacity and improve achievement for effective and qualitative delivery in STEM classrooms. We focus on the two primary stakeholders in teaching and learning in the university who are students and lecturers. This manuscript explores the causes of underachievement among undergraduates in STEM fields by employing a mixed methods for data collection and analysis among 150 undergraduates and 45 lecturers from six public universities using purposive and quota sampling. Three main research questions were raised on student, lecturer and institution base factors along with perceived hindrances to STEM learning and teaching. Three instruments; Students Factors for Underachievement (SFUA), Lecturers Factor for Underachievement (LFUA) and Lecturers Perceived Factors for Underachievement (LPFU) were employed for data collection through survey and interview. Among other findings, poor prior knowledge among learners, non-utilisation of instructional resources, inaccessibility to library and laboratory and it resources were principal hindrances of undergraduates, lecturers and institution-base factors. The study concluded that efforts and better commitment is required from stakeholders to alleviate the present inadequacies and recommend interventions to remediate areas of need.