This book constitutes the refereed proceedings of the Second International and Interdisciplinary Conference on Modeling and Using Context, CONTEXT'99, held in Trento, Italy, in September 1999.The 33 revised full papers and 21 revised short papers presented were carefully reviewed and selected from a total of 118 papers submitted. The papers address all current aspects of context in various areas such as artificial intelligence, formal logics, computer science, computational linguistics, cognitive science, pragmatics, and philosophy.