Identifying transtheoretical mechanisms of self-compassion is important for understanding its use as a treatment approach for depression and anxiety. This study examined the effectiveness of self-compassion and detached reappraisal on mechanisms involved in the processing of rejection, namely attention, appraisals, and affect. Rejection is a common experience that can increase individuals risk for poor mental health outcomes, especially among those with rejection sensitivity. Outcomes are framed within the Situated Action Cycle, which offers an integrated approach to examining mechanisms of cognitive, affective, and behavioral processing. Online participants who reported at least moderate levels of rejection sensitivity were recruited to participate in the study. Study 1 documented that recalling an experience of rejection led to rejection-related emotions as opposed to conflict-related emotions, as expected. Additionally, a brief self-compassion writing induction produced expected increases in state self-compassion and positive affect, but also unexpected increases in state reappraisal. A brief detached reappraisal induction led to unexpected decreases in state reappraisal, particularly for those with marginalized identities. Study 2, which included a neutral control condition, found that brief self-compassion training increased negative attention bias and controllability appraisals and decreased positive affect. Detached reappraisal led to greater reductions in positive affect compared to both self-compassion and control conditions. Further, detached reappraisal led to increases in negative affect compared to the self-compassion condition. Changes observed from pre- to post-intervention in attentional, cognitive, and affective measures were not sustained following a Cyberball rejection manipulation administered one day later. Results from the study reveal nonsuperior effects of either intervention and possible mechanisms of self-compassion interventions for individuals with rejection sensitivity. Self-compassion may be a useful strategy to help individuals with rejection sensitivity attend to the negative emotions experienced during rejection with greater equanimity but may lead to reductions in positive affect. Further work is needed to determine whether the potential benefits of continued self-compassion training outweigh the mixed effects of brief self-compassion training and whether such benefits are superior to other evidence-based approaches.