This paper argues for a mild perfectionism in applying Amartya Sen's capability approach for an education transformative of student agency and well-being. Key to the paper is the significance of education as a process of being and becoming in the future, and education's fundamental objective of a positively changed human being. The capability approach therefore provides for additional reasons for investment in education beyond its human capital value. While the capability approach offers a radical freedom-focused approach to education, it is argued here that because it is an approach to "human" development and not a theory of "educational" development, it provides a thin account of education and how power and unfreedoms work in education. What is then appropriate in the specific case of education is neither Sen's reluctance to specify valuable capabilities, nor Nussbaum's canonical list of 10 universal capabilities, but a mild perfectionism which steers a path between these two approaches and yet is consistent with the core quality of life and well-being arguments of the capability approach. The argument proceeds through stages of outlining the capability approach and then exploring arguments around power, values and education as a public good, before arguing that capability pedagogical praxis as a practical expression of the theoretical ideas would inflect towards social justice in education.