Since the publication of Hans Reichenbach's definitive books on the philosophy of the theory of relativity during the nineteen twenties,¹ the literature on the philosophy and history of Einstein's special theory of relativity (hereafter called STR) has been enlarged by contributions which call for critical evaluation. In this chapter, I shall give such an evaluation in the course of presenting: (a) an up-to-date analysis of the intertwined philosophical and empirical foundations of the kinematics of the STR, with attention to neglected issues and prevalent misconceptions, and (b) a demonstration that a rigorous grasp of the philosophical conceptions underlying the fully evolved STR and distinguishing it from its ancestors is decisively prerequisite to (1) the very posing of well-conceived, searching historical questions in regard to the STR, and hence to (2) the provision of a historically sound and illuminating account of its genesis.