Caregivers of cancer patients face challenges impacting their physical, psychological and social well-being that need attention in the form of well-designed and tested interventions. We created an eight-session individual stress management intervention for caregivers of allogeneic hematopoietic stem cell transplant (Allo-HSCT) recipients. This intervention, tested by randomized control trial, proved effective in decreasing distress. Herein, we describe the intervention including theoretical framework, development, and elements of fidelity. Implementation challenges along with recommendations for refinement in future studies are discussed with the goal of replication and dissemination. Seventy-four of 148 caregivers received stress management training following randomization. The intervention occurred during the 100-day post-transplant period when caregivers are required. The training provided integrated cognitive behavioral strategies, psychoeducation, and problem-solving skills building as well as use of a biofeedback device. Seventy percent of caregivers completed all eight sessions indicating good acceptability for the in-person intervention; however, most caregivers did not reliably use the biofeedback device. The most common reason for drop-out was their patient becoming gravely ill or patient death. Few caregivers dropped out because of study demands. The need for flexibility in providing intervention sessions was key to retention. Our evidence-based stress management intervention for Allo-HSCT caregivers was feasible. Variability in acceptability and challenges in implementation are discussed and suggestions for refinement of the intervention are outlined. Dissemination efforts could improve by using alternative methods for providing caregiver support such as telephone or video chat to accommodate caregivers who are unable to attend in-person sessions.