Gaining an in-depth understanding of users is critical for building artificial intelligence systems. With the rapid development of positioning, sensing and social networking technologies, large quantities of human behavioral data are now readily available. They reflect various aspects of human mobility and activities in the physical world. The availability of this data presents an unprecedented opportunity to user understanding. In addition, recent studies in psychology suggest that numerous psychological features, such as personality traits, are highly correlated to user behaviors. It will be interesting to study how we can design computational frameworks for inferring psychological features of users, based on their data at different levels and across heterogeneous domains, and how these frameworks can benefit the development of artificial intelligence systems. In this session, we plan to invite researchers from computer science, psychology and cognitive science areas. We will brainstorm innovative ideas, technologies, systems and applications along this interdisciplinary research direction.