This volume presents a collection of thoroughly reviewed revised full papers on automated deduction in classical, modal, and many-valued logics, with an emphasis on first-order theories. Five invited papers by prominent researchers give a consolidated view of the recent developments in first-order theorem proving. The 14 research papers presented went through a twofold selection process and were first presented at the International Workshop on First-Order Theorem Proving, FTP'98, held in Vienna, Austria, in November 1998. The contributed papers reflect the current status in research in the area; most of the results presented rely on resolution or tableaux methods, with a few exceptions choosing the equational paradigm.