This volume constitutes the proceedings of the Fourth International Conference on Algebraic and Logic Programming (ALP '94), held in Madrid, Spain in September 1994. Like the predecessor conferences in this series, ALP '94 succeeded in strengthening the cross-fertilization between algebraic techniques and logic programming. Besides abstracts of three invited talks, the volume contains 17 full revised papers selected from 41 submissions; the papers are organized into sections on theorem proving, narrowing, logic programming, term rewriting, and higher-order programming.