This volume contains the papers presented at the Second International and - terdisciplinary Conference on Modeling and Using Context (CONTEXT'99), held in Trento (Italy) from 9 to 11 September 1999. CONTEXT'99 is the second in the CONTEXT series. The rst was held in Rio de Janeiro (Brazil) in 1997. The CONTEXT conference series is meant to provide an interdisciplinary - rum where researchers can exchange ideas, methodologies, and results on c- text, and is increasingly becoming an important reference for all people doing research on context. This is testi ed by the larger number of research...