The blurring of lines between nonprofits, governments, and for-profit businesses have fueled contemporary social innovation. With this convergence of market and non-market practices, we find that cross-sector collaborations provide for lasting solutions to our society's most vexing social problems. In this audio lecture, sponsored by the Stanford Center for Social Innovation, Kriss Deiglmeier, Executive Director of the CSI, defines social innovation, bringing clarity to the term, and examines its current status in theory and practice.