The 13-item Appearance-Related Social Media Consciousness Scale (ASMC Scale; Choukas-Bradley et al., 2020) assesses appearance-related social media consciousness (ASMC) – i.e., ongoing awareness of one’s physical attractiveness to an online audience. The ASMC Scale can be administered online or in-person to adolescents and adults and is free to use in any setting. In this chapter, we discuss the development of the scale and provide evidence of its psychometric properties. The ASMC Scale is unidimensional, with evidence of partial measurement invariance across gender (comparing girls/women and boys/men). Internal consistency reliability, test-retest reliability, convergent validity, discriminant validity, and incremental validity support the use of the scale with adolescents and adults. Next, we provide the ASMC Scale items in their entirety, instructions for administering the scale to participants, the response scale, the scoring procedure, and information about known translations (Chinese/Mandarin, Spanish, Turkish). Additionally, we provide logistical information, such as permissions, copyright, contact information, and considerations for alterations (e.g., related to short-term video-based social media). We also discuss initial findings related to ASMC, including gender differences in mean levels (with girls/women reporting higher levels of ASMC than boys/men), and evidence of associations between ASMC and offline body image and mental health constructs.