IT use is an important concept both in research and in practice. Yet, IT use has been simply defined and measured in IS research. Presently used measurements do not reflect the dynamics of users’ IT use behavior, which are important and account for job performance. This research aims at conceptualizing a new construct to capture the changes in IT use and developing an instrument for it. From an adaptive structuration perspective, we propose a new construct named Adaptive IT Use (AITU) to capture use changes in both IT feature set (size, content, and network), and the spirit of IT features. We further propose six dimensions of AITU and corresponding measuring items. After interviews and card-sorting experiments, an instrument of AITU is developed.