The Inputs-Outputs interdisciplinary conference on engagement (and related terms) was structured to cross-fertilise the relevant researchers from the arts, sciences and engineering on the causes, consequences and assessment of engagement. The goal of the conference was to encourage interdisciplinary research and collaboration on engagement, presence, immersion, interest, cognitive absorption, motivation (educational), vigilance and user-experience. Three themes emerged from the juxtaposition of this broad group of academics and practitioners: 1) Challenge, in many cases, aids the creation of engagement. 2) The consequences arising from engagement are often fundamentally social. 3) The measurement and assessment of engagement is advancing via engineering and computer science.