This chapter traces the nature-nurture controversy in the classical version of cultural-historical psychology and its modern derivatives. It explores many different derivative developments rooted in the work of Lev Vygotsky and his contemporaries and focuses on the interconnected work of Piotr Galperin, Daniil Elkonin, Vasily Davydov, and their colleagues. Both Galperin and Elkonin were in close and productive collaboration with Vygotsky in the early 1930s. The Vygotsky-Galperin-Elkonin work on teaching-learning and development and with particular emphases on the role of cultural tools in these processes was continued in Davydov's 'developmental teaching theory', which pertains to types of generalization in instruction. The central concept of the developmental teaching theory is that of the learning activity. Learning activity in its narrow meaning includes educational practices and experiences that are designed to empower a young learner and to stimulate his capacity to remain a learner for life.