This volume contains most of the papers presented at the Twelfth International Workshop on Maximum Entropy and Bayesian Methods held in Paris, July 1992. As was the case with the eleven previous annual workshops (the first was held in 1980) this twelfth workshop brought together leading scientists and `newcomers' involved in research activities in diverse scientific disciplines in which the theory and applications of maximum entropy and Bayesian statistics plays a significant and fruitful role. The contributions are presented in six sections: Bayesian Inference and Maximum Entropy (18 papers); Quantum Physics and Quantum Information (9 papers); Time Series (3 papers); Inverse Problems (4 papers); Applications (11 papers); Image Restoration and Reconstruction (9 papers). The rich diversity of the papers presented, and the status of many of the contributors, attest to the growing importance and vigour of this major topic to many areas of applied science and engineering. This volume will be of interest to a wide range of researchers whose work involves the theory and applications of maximum entropy and Bayesian statistics.