Contents: Part I:Representation and Constraint in Complex Processing.S.M. Kosslyn, M.A. Sokolov, J.C. Chen, The Lateralization of BRIAN: A Computational Theory and Model of Visual Hemispheric Specialization. P.A. Carpenter, M.A. Just, The Role of Working Memory in Language Comprehension. K. Kotovsky, D. Fallside, Representation and Transfer in Problem Solving. K. Dunbar, D. Klahr, Developmental Differences in Scientific Discovery Processes. G.A. Miller, Scientists of the Artificial. Part II:Expertise in Human and Artificial Systems.E.A. Feigenbaum, What Hath Simon Wrought?. N. Charness, Expertise in Chess and Bridge. J.R. Hayes, Writing Research: The Analysis of a Very Complex Task. K.A. Ericsson, J.J. Staszewski, Skilled Memory and Expertise: Mechanisms of Exceptional Performance. R. Glaser, Expertise and Learning: How Do We Think About Instructional Processes Now That We Have Discovered Knowledge Structures? Part III:Instruction and Skill Acquisition.J.G. Greeno, Situations, Mental Models, and Generative Knowledge. J.H. Larkin, Display-Based Problem Solving. J.R. Anderson, The Analogical Origins of Errors in Problem Solving. Part IV:Science and Thought.H.A. Simon, The Scientist as Problem Solver. A. Newell,Epilogue.Putting It All Together. A. Newell, How It All Got Put Together.