Described herein are deuterium-enriched neuroactive steroids of the Formula (II) or a pharmaceutically acceptable salt thereof wherein R2a, R2b, R3, R4a, R4b, R5, R6a, R6b, Rlla, Rllb, R12a, R12b, R16a, R16b, R17, R19, Ra, and Rb and subvariables thereof are as defined herein. Such compounds are envisioned, in certain embodiments, to behave as GABA modulators. The present invention also provides pharmaceutical compositions comprising a compound of the present invention and methods of use and treatment.