Abstract: HOL-Boogie — An Interactive Prover for the Boogie Program Verifier Sascha Böhme and Rustan Leino and Burkhart Wolff Boogie is a program verification condition generator for animperative core language. It has front-ends for the programming languagesC# and C enriched by annotations in first-order logic.Its verification conditions — constructed via a wp calculus from these annotations — are usually transferred to automated theorem proverssuch as Simplify or Z3. In this paper, however, we present a proof-environment,HOL-Boogie, that combines Boogie with the interactivetheorem prover Isabelle/HOL. In particular, we present specific techniquescombining automated and interactive proof methods for code-verification.We will exploit our proof-environment in two ways: First, we present scenariosto &duml;ebug" annotations (in particular: invariants) by interactiveproofs. Second, we use our environment also to verify &buml;ackground theories", i.e. theories for data-types used in annotations as well as memoryand machine models underlying the verification method for C.