The proposed Histiocytic Disorders Workshop is an unprecedented gathering of physicians and scientists—across adult and pediatric diseases, HLH and histiocytic neoplasms—eager to align priorities and approaches to research in these diseases. The two-day event will include approximately 50 in-person attendees including histiocytosis scholars, patients and stakeholders, experts in patient engagement and patient-reported outcomes, diversity and inclusion, junior career development, and representatives from industry as well as from federal agencies.