This book constitutes the proceedings of the Second International Conference on Abstract State Machines, B and Z, which took place in Orford, QC, Canada, in February 2010. The 26 full papers presented were carefully reviewed and selected from 60 submissions. The book also contains two invited talks and abstracts of 18 short papers which address work in progress, industrial experience reports and tool descriptions. The papers cover recent advances in four equally rigorous methods for software and hardware development: abstract state machines (ASM), Alloy, B and Z. They share a common conceptual framework, centered around the notions of state and operation, and promote mathematical precision in the modeling, verification and construction of highly dependable systems.