The 27th annual International Conference on Human Factors in Computing (CHI) convened in Boston, MA (USA) from April 4-9, 2009. Included in this year’s technical program was a special interest group (SIG) meeting on API usability. This report summarizes the SIG, emphasizing the primary takeaways, which include a greater understanding of the types of APIs, case studies, and a place to share our multi-disciplinary results.