Pediatric blood cancer diagnosis is a stressful experience for families as it can involve urgent treatment that can be life-threatening and require extended hospital stays. Little is known about the experiences of parent caregivers of children with a blood cancer during the diagnosis period and how families’ needs may differ in light of the patient’s developmental phase in the life span. We conducted semistructured in-depth interviews with 20 parent caregivers (aged 30-65) of children diagnosed with a blood cancer, recruited through The Leukemia & Lymphoma Society’s (LLS) constituency. Interview transcripts were thematically analyzed using the constant comparative method. To elucidate similarities and differences in caregiving experiences, findings were compared across parents with children diagnosed in three developmental periods: infancy-early childhood, age 0-6 ( = 9); pre-early adolescence, aged 9-14 ( = 5); and late adolescence-emerging adulthood, aged 16-27 ( = 6). Across all developmental periods, parents described three similar caregiving experiences during the diagnosis period: , , and Among caregivers of younger children, persistence was motivated by parental intuition and challenges included coping with traumatic physical and psychological impacts of treatment procedures. For caregivers of late adolescents-early adults, persistence was motivated by the child’s self-assessment and fertility-related concerns emerged. Results illustrate core issues for parent blood cancer caregivers and highlight ways to tailor supportive resources that facilitate good communication practices and shared decision-making to children’s distinct developmental needs.