Introduction: Respectful maternity care (RMC) during childbirth is an integral component of quality of care. However, women's experiences of mistreatment are prevalent in many low- and middle-income countries. This is a complex phenomenon that has not been well explored from a behavioral science perspective. We aimed to understand the behavioral drivers of mistreatment during childbirth among maternity care staff at public health facilities in the Sindh province of Pakistan. Methods: Applying the COM-B (capability-opportunity-motivation that leads to behavior change) model, we conducted semistructured in-depth interviews among clinical and nonclinical staff in public health facilities in Thatta and Sujawal, Sindh, Pakistan. Data were analyzed using thematic deductive analysis, and findings were synthesized using the COM-B model. Results: We identified several behavioral drivers of mistreatment during childbirth: (1) institutional guidelines on RMC and training opportunities were absent, resulting in a lack of providers' knowledge and skills; (2) facilities lacked the infrastructure to maintain patient privacy and confidentiality and did not permit males as birth companions; (3) lack of provider performance monitoring system and patient feedback mechanism contributed to providers not feeling appreciated or recognized. Staff bias against patients from lower castes contributed to patient abuse and mistreatment. The perspectives of clinical and nonclinical staff overlapped regarding potential drivers of mistreatment during childbirth. Conclusions: Addressing mistreatment during childbirth requires improving the knowledge and capacity of maternity staff on RMC and psychosocial support to enhance their understanding of RMC. At the health facility level, governance and accountability mechanisms in routine supervision and monitoring of staff need to be improved. Patients' feedback should be incorporated for continuous improvement in providing maternity care services that meet patients' preferences and needs.