While there is extensive research exploring factors that act to facilitate or hinder bystander intervention in sexual violence contexts, there is limited research on these factors in the context of image-based sexual abuse. In this chapter, we report on the survey and focus group data from the Image-Based Sexual Abuse and Bystander Intervention Study relating to actual and perceived experiences of witnessing and intervening in image-based sexual abuse contexts. This includes detailing findings around whether participants reported having witnessed image-based sexual abuse, and if so, whether they said or did anything (and details of what they said or did, where relevant). We also report on the factors that act to facilitate or hinder the perceived likelihood of bystander intervention in hypothetical scenarios, such as the nature of the relationship between parties, fear to personal safety, the role of other bystanders, and beliefs regarding the laws on image-based sexual abuse.