Background: De-implementation requires understanding and targeting multilevel determinants of low-value care. The objective of this study was to identify multilevel determinants of imaging for prostate cancer (PCa) and asymptomatic microhematuria (AMH), two common urologic conditions that have contributed substantially to the approximately $30 billion spent annually on unnecessary imaging in the US. Methods: We used a convergent mixed-methods approach involving survey and interview data. Using a survey, we asked 33 clinicians (55% response rate) to indicate their imaging approach to 8 clinical vignettes designed to elicit responses that would demonstrate guideline-concordant/discordant imaging practices for patients with PCa or AMH. A subset of survey respondents (N=7) participated in semi-structured interviews guided by a combination of two frameworks that offered a comprehensive understanding of multilevel implementation determinants. We analyzed the interviews using a directed content analysis approach. We then identified themes to better understand the differences and similarities in the imaging determinants across the two clinical conditions. Results: Survey results showed that the majority of clinicians chose guideline-concordant imaging behaviors for PCa, guideline-concordant imaging intentions were more varied for AMH. Imaging decisions for both PCa and AMH were often driven by national guidelines from major professional societies. However, when clinicians felt that guidelines were inadequate, they reported that their decision-making was influenced by their knowledge of recent scientific evidence, past clinical experiences, and the anticipated benefits of imaging (or not imaging) to both the patient and the clinician. In particular, clinicians referred to patients’ anxiety and uncertainty which were, at times, resolved through more intensive diagnostic imaging. Patients’ clinical factors also informed clinicians’ imaging decisions. For AMH patients, clinicians additionally expressed concerns regarding legal liability risk. Conclusions: Our study identified comprehensive multilevel determinants of imaging to inform development of de-implementation interventions to reduce low-value imaging, which we found useful for identifying determinants of de-implementation. De-implementation interventions should be tailored to address the contextual determinants that are specific to each clinical condition.