Each year, the IACC releases its annual list of scientific advances that represent significant progress in the field. The 20 studies selected have given new insight into the underlying biology of autism spectrum disorder (ASD) and potential risk factors, examined the state of the science in early screening and diagnosis, and evaluated promising early intervention strategies. The advances also address health outcomes for children and adults with autism, and issues related to education, transition to adulthood, and employment. The 2015 Summary of Advances provides short, plain language summaries of the top research breakthroughs selected by the IACC from a pool of research articles nominated by the members. Articles are grouped according to the topics represented by the questions of the IACC Strategic Plan for ASD Research. Citations for the articles selected for the Summary of Advances, as well as a complete listing of those nominated, are included at the end of the document.