Xiong Shili (1885-1968) is widely recognized as a founding figure of the modern New Confucian school of philosophy and seen by many as one of the most important and creative Chinese philosophers of the twentieth century. His ultimate concern throughout his long intellectual career was to show that "Reality (ti) and function (yong) are non-dual." Reality is the "locus" that ontologically grounds the phenomenal yet is not different from the phenomenal. His onto-cosmology draws syncretically on a diverse range of resources in the Chinese philosophical tradition to construct his own overarching metaphysical vision, articulated within the broader context of advancing a systematic critique of both Madhyamaka and Yog=ac=ara Buddhist thought, the culmination of nearly four decades of critical engagement. Treatise on Reality and Function (Ti yong lun) is the mature expression of Xiong's signature metaphysical doctrine. Published in 1958, Xiong considered it to be his most important philosophical achievement, but it has never before appeared in English. This annotated translation by John Makeham presents the text along with the original foreword attributed to Han Yuankai, and Xiong's original preface.