The contribution focuses on a prominent feature in ICL practice—cumulative charges and convictions—which best confirms the presumption of this book concerning the close inter-relationship as between substantive and procedural ICL. This chapter addresses issues that arise when considering this practice, with respect to instances where both war crimes and crimes against humanity charges are based on the same underlying conduct, from the perspective of the promotion of adherence to IHL, as one of the goals of the war crimes regime in ICL. The chapter argues that the adoption of a strict policy for cumulative charges and convictions, based on a rigid, technical jurisprudential test, is not conducive to ensuring results that are sufficiently attuned to the circumstances of each case. It surveys the recent proceedings in the Ongwen case before the ICC and discusses the Court’s failure to provide more comprehensive doctrinal guidance in this regard. The author proposes the adoption of a more nuanced approach when contemplating cumulative charges for these two categories of crimes that involves an in-depth examination of the “nexus to an armed conflict” requirement of war crimes.