A sizable portion of adults living with chronic medical conditions (CMCs) delay initiation of care or maintain it inconsistently, which has tremendous personal and public costs. However, few explanatory models with high yield for intervention development and implementation have been proposed to date that would help to characterize and support care use for CMCs. A situated Information, Motivation, Behavioral Skills model of Care Initiation and Maintenance (sIMB-CIM) is presented here as an application of the IMB model to medical care use for CMCs. An example of a sIMB model for characterizing and intervening to support maintenance in HIV-care is provided.