Fuzzy logic control systems have been applied as an effective control system in various fields, including vibration control of structures. The advantage of this approach is its inherent robustness and ability to handle nonlinearities and uncertainties in structural behavior and loading. In this paper, the design of a multiobjective optimal fuzzy logic controller (FLC) for seismically excited building structures has been discussed. Acceleration and velocity information have been used as feedback to the FLC. Minimization of the peak acceleration and displacement response of the structure, nondimensionalized by an uncontrolled peak acceleration and displacement response, respectively, have been used as the two objectives. A two-branch tournament genetic algorithm has been used to find a set of Pareto-optimal solutions. The proposed multiobjective optimal FLC has been verified on a benchmark problem, namely, a "scaled model of a three-story building with an active mass driver system," and the results have been compared with the results from other control methods reported in the literature. It has been shown that the use of acceleration information, in addition to velocity as a feedback for the FLC, results in better structural performance.