This study describes the development and initial psychometric evaluation of the Eating for Muscularity Scale (EMS), a measure of muscularity-oriented disordered eating (MDE) attitudes and behaviors. We conducted a literature review to define the construct of MDE and relevant subdomains. This review informed a large pool of items addressing these subdomains, which were then reduced based on feedback from subject-matter experts. Confirmatory factor analyses (CFA) were conducted to refine the measure and identify latent factors in 2 samples of participants recruited online. Preliminary psychometric evaluation of EMS items was conducted in a subset of the original sample ( = 266). CFA supported a 27-item short form of the measure. The EMS demonstrated high internal consistency (Cronbach's α = .95), moderate to strong concurrent validity with related measures = .43-.78), good construct validity using known-group assessment, and strong test-retest reliability ( = .90). These findings provide preliminary support for the EMS as a reliable and valid measure of MDE. The instrument has the potential to support future research to improve clinical understanding and assessment of MDE and its etiology, prevalence, and treatment outcomes. Further studies are required to evaluate the clinical and research utility of the scale. (PsycInfo Database Record (c) 2020 APA, all rights reserved).