This volume contains the proceedings of HCVS 2014, the First Workshop on Horn Clauses for Verification and Synthesis which was held on July 17, 2014 in Vienna, Austria as a satellite event of the Federated Logic Conference (FLoC) and part of the Vienna Summer of Logic (VSL 2014). HCVS 2014 was affiliated to the 26th International Conference on Computer Aided Verification (CAV 2014) and to the 30th International Conference on Logic Programming (ICLP 2014). Most Program Verification and Synthesis problems of interest can be modeled directly using Horn clauses and many recent advances in the Constraint/Logic Programming and Program Verification communities have centered around efficiently solving problems presented as Horn clauses. Since Horn clauses for verification and synthesis have been advocated by these communities in different times and from different perspectives, the HCVS workshop was organized to stimulate interaction and a fruitful exchange and integration of experiences.