This book constitutes the refereed post-proceedings of the First International Conference on Hardware Verification, Software Testing, and PADTAD held in November 2005. The conference combines the sixth IBM Verification Workshop, the fourth IBM Software Testing Workshop, and the third PADTAD (Parallel and Distributed Systems: Testing and Debugging) Workshop. The 14 revised full papers presented together with three invited contributions were carefully reviewed and selected from 31 submissions. The papers address all current issues in hardware/software verification, software testing, and testing of parallel and concurrent applications.