While virtual humans are proven tools for training, education and research, they are far from realizing their full potential. Advances are needed in individual capabilities, such as character animation and speech synthesis, but perhaps more importantly, fundamental questions remain as to how best to integrate these capabilities into a single framework that allows us to efficiently create characters that can engage users in meaningful and realistic social interactions. This integration requires in-depth, inter-disciplinary understanding few individuals, or even teams of individuals, possess. We help address this challenge by introducing the ICT Virtual Human Toolkit, which offers a flexible framework for exploring a variety of different types of virtual human systems, from virtual listeners and question-answering characters to virtual role-players. We show that due to its modularity, the Toolkit allows researchers to mix and match provided capabilities with their own, lowering the barrier of entry to this multi-disciplinary research challenge.