REDLOG is a package that extends the computer algebra system REDUCE to a computer logic system, i.e., a system that provides algorithms for the symbolic manipulation of first-order formulas over some temporarily fixed language and theory. In contrast to theorem provers, the methods applied know about the underlying algebraic theory and make use of it. We illustrate some applications of REDLOG , describe its functionality as it appears to the user, and explain the design issues and implementation techniques. REDLOG is available on the WWW.