The present disclosure provides compounds of any one of Formulae (I), (II),and (III). The compounds described herein are inhibitors of histonemethyltransferases (e.g.,enhancer of zeste homolog 1 (EZH1) and enhancer of zeste homolog 2 (EZH2)) andareuseful in treating and/or preventing a broad range of diseases (e.g.,proliferative diseases). Alsoprovided in the present disclosure are pharmaceutical compositions, kits,methods, and usesincluding or using a compound described herein.