This proceedings volume contains results presented at the Sixth International Workshop on Data Analysis in Astronomy ¿ ¿Modeling and Simulation in Science¿ held on April 15-22, 2007, at the Ettore Majorana Foundation and Center for Scientific Culture, Erice, Italy. Recent progress and new trends in the field of simulation and modeling in three branches of science ¿ astrophysics, biology, and climatology ¿ are described in papers presented by outstanding scientists. The impact of new technologies on the design of novel data analysis systems and the interrelation among different fields are foremost in scientists' minds in the modern era. This book therefore focuses primarily on data analysis methodologies and techniques.