Entrepreneurship has been positioned as a panacea to the economic development challenges facing Nigeria. Subsequent Nigerian governments have sought to foster a vibrant entrepreneurial class by investing in entrepreneurship education at the tertiary level. While that investment has yielded increased levels of entrepreneurial participation, it has had limited impact in terms of entrepreneurial business growth. Thus, there emerges a need to understand what factors influence entrepreneurial business growth in Nigeria and how successful Nigerian entrepreneurs learn to grow their businesses to inform future national human resource development (NHRD) policy. Consequently, this study explored how successful entrepreneurs in Nigeria learn to grow a business and identified what knowledge, skills, and abilities they used to facilitate business growth. In addition, the study explored the factors that Nigerian entrepreneurs thought influenced business growth. Using grounded theory as a research methodology, I conducted interviews with twenty successful Nigerian entrepreneurs to obtain data. The data indicated that successful Nigerian entrepreneurs are self-directed learners who engaged in a range of learning activities in which micro-learning processes incidentally occur. Further, participants identified eight task-related knowledge, skills, and abilities they relied on to succeed. They described five factors they believed influenced entrepreneurial business growth and noted that these factors influenced business growth in different ways. The data suggested that the human capital of the entrepreneur mediates the influence of the business environment on enterprise growth. Further, the data strongly indicated that the human capital of the entrepreneur, conceived as discrete task-related knowledge, skills, and abilities developed over time, was the most important factor that determined whether business growth occurred. Overall, the study advances our understanding of the role of learning in entrepreneurial growth in Nigeria and highlights the need to develop holistic NHRD policies that seek to develop the human capital of the entrepreneur, and the institutional environment to increase entrepreneurial success in Nigeria and engender economic development. The study offers recommendations for policy makers, educators in Nigerian Universities, entrepreneurs at large, and suggestions for future research.