The Self-Injurious Thoughts and Behaviors Interview (SITBI) is a widely used measure of the presence, frequency, and characteristics of suicide and self-harming thoughts and behaviors. In response to advances in the conceptualization of these outcomes, and the potential for online data collection, we created a revised version of the SITBI (SITBI-R) and tested its psychometric properties via in-person interview and online self-report formats. Across two studies, the SITBI-R demonstrated strong psychometric properties for both assessment formats. In Study 1, outcomes measured via the SITBI-R showed convergent validity with those assessed with the Columbia Suicide Severity Rating Scale, another interview assessing suicidal thoughts and behaviors. The SITBI-R also showed strong alternate-forms reliability across nearly all outcomes assessed via both assessment formats. In Study 2, the SITBI-R showed strong test-retest reliability via the online assessment format. Across both studies, reliability was strongest for more recent outcomes (e.g., past year vs. lifetime) and for more commonly assessed outcomes of suicidal thoughts, plans, and attempts than for other, less commonly assessed behaviors (e.g., suicide gestures, interrupted suicide attempts, and aborted suicide attempts). The results of these two studies suggest that the SITBI-R provides reliable and valid measurement of key self-injurious outcomes both in person and online. (PsycInfo Database Record (c) 2020 APA, all rights reserved).