Sustainment of daily routines requires greater psychological resilience and may lead to greater resilience in the face of stressors. Existing scales tend only to focus on emotions and engagement, rather than how well individuals sustain routine behaviors. To address this gap in the literature, we developed the Sustainability of Living Inventory (SOLI). A pool of 46 Likert-type items were developed to indicate how regularly respondents performed a variety of specific routines. Four separate study samples were collected through online surveys with community-dwelling American adults (N = 1,109). The final model evidenced excellent goodness-of-fit and consisted of 42 items, which loaded on eight dimensions: Hygiene, eating, sleep, duties at home, leisure at home, exercising, social activities, and work/study involvement (α = .73-.93). These eight dimensions further loaded on two second-order factors, primary and secondary daily routines. Convergent validity was demonstrated in the correlations with Lawton Instrumental Activities of Daily Living Scale, Perceived Ability to Cope with Trauma Scale, Savoring Beliefs Inventory, and Conservation of Resources-Evaluation. Discriminant validity was demonstrated in the correlations with the List of Threatening Experiences, Life Events Checklist for DSM-5, and items on chronic financial strain. Criterion-related validity was demonstrated in the correlations with established outcome measures including State-Trait Anxiety Inventory, Patient Health Questionnaire, PTSD Checklist-Civilian Version, Positive and Negative Affect Schedule, Satisfaction with Life Scale, and Perceived Stress Scale. Incremental validity was shown in the correlations with outcome measures independent of common coping and resource variables. Implications of the SOLI on mental health screening and intervention were discussed.