BACKGROUND: In India, despite several effective interventions being implemented, pneumonia persists as a major cause of under-five mortality. We explore barriers and facilitators to implementing a childhood pneumonia management program in a North Indian district. The study aims to inform the development of effective implementation strategies for pneumonia management in resource-constrained settings. METHODS: This mixed-method study was conducted during the formative phase of an ongoing pre-post quasi-experimental implementation study. Data collection followed the Consolidated Framework for Implementation Research, encompassing surveys on implementation climate and attitudes toward evidence-based-treatment for childhood pneumonia, as well as in-depth interviews to uncover implementation barriers and facilitators with healthcare staff. Additionally, a baseline cross-sectional facility inventory survey was conducted in 26 government healthcare facilities. We present descriptive statistics from the surveys along with deductive analysis findings from qualitative interviews. RESULTS: Several barriers were observed, like deficient infrastructure and limited space, privacy concerns, inadequate examination tables, disrupted medicine supply, non-maintenance of under-five children's records, inadequate utilization of the digital portal for pneumonia case registration, lack of specific budget allocation for medicine procurement, absence of functional equipment, staff shortages, lack of training, referral linkage issues, and limited accessibility to guideline materials. The absence of incentives demotivated community healthcare workers (CHWs), while coordination issues, power dynamics, and unclear job responsibilities affected the motivation of other healthcare staff. Community reluctance to seek care from government facilities and diminishing community-level trust in CHWs posed implementation challenges. Facilitators included committed healthcare and community workers, problem-solving skills, community engagement, and untied funds from the district government. Implementation climate scores were mildly positive, yet provider attitudes towards Evidence-Based Practices Adoption were neutral. CONCLUSIONS: We propose a multi-pronged approach including healthcare provider training, task sharing, budget reallocation promoting medication access, performance monitoring, digitalization of the record system, and community engagement to optimize program effectiveness. TRIAL REGISTRATION: This research was prospectively registered in the clinical trial registry CTRI202103031622 [Registered on: 01/03/2021].