Charles River Analytics and our partners at Massachusetts General Hospital and Virtual Reality Medical Center propose to design and demonstrate Constructed Environments for Successfully Sustaining Abstinence Through Immersive and On-Demand Treatment (CESSATION). We will build VR environments using our in-house game engine and content (cues) that are diverse, realistic, and well-placed, bolstering traditional psychological therapy delivery, and use research-based principles of narrative and game design to produce immersive and engaging content to motivate continued use. We will use probabilistic models (e.g., Bayesian networks) and machine-learning (e.g., neural nets) to learn from patient data and clinician input to assist in selecting and combining therapies in a way that is tailored to the individual patient. Finally, CESSATION will communicate information to clinicians in a manner that is understandable, and gives them enough meta-information to foster appropriate trust in the system. The anticipated results of the proposed Phase I work are: (1) an initial domain analysis; (2) initial VR content; (3) initial motivational content; (4) prototype sensor capabilities; (5) a prototype Intervention Tailoring Component; (6) a prototype Clinician User Interface and Remote Patient Data Server; and (7) an initial Phase I CESSATION prototype demonstration and evaluation.