This book constitutes the thoroughly refereed post-proceedings of the Second International Symposium on Unifying Theories of Programming, UTP 2008, held at Trinity College, Dublin, Ireland, in September 2008. The 15 revised full papers presented, together with two invited talks, were carefully reviewed and selected from 20 submissions. Based on the pioneering work on unifying theories of programming of Tony Hoare, He Jifeng, and others, the aims of this Symposium series are to continue to reaffirm the significance of the ongoing UTP project, to encourage efforts to advance it by providing a focus for the sharing of results by those already actively contributing, and to raise awareness of the benefits of such a unifying theoretical framework among the wider computer science and software engineering communities.