BACKGROUND: Timely diagnosis and treatment of pediatric tuberculosis (TB) is critical to reducing mortality but remains challenging in the absence of adequate diagnostic tools. Even once a TB diagnosis is made, delays in treatment initiation are common, but for reasons that are not well understood. METHODS : To examine reasons for delay post-diagnosis, we conducted semi-structured interviews with Ministry of Health (MoH) physicians and field workers affiliated with a pediatric TB diagnostic study, and caregivers of children aged 0-14 years who were diagnosed with pulmonary TB in Lima, Peru. Interviews were analyzed using systematic comparative and descriptive content analysis. RESULT S : We interviewed five physicians, five field workers and 26 caregivers with children who initiated TB treatment , 7 days after diagnosis (n = 15) or who experienced a delay of ≥7 days (n=11). Median time in delay from diagnosis to treatment initiation was 26 days (range 7-117). Reasons for delay included: Health systems challenges (administrative hurdles, medication stock, clinic hours), burden of care on families and caregiver perceptions of disease severity. CONCLUS ION: Reasons for delay in treatment initiation are complex. Interventions to streamline administrative processes and tools to identify and support families at risk for delays in treatment initiation are urgently needed.