Objective: Hematopoietic stem cell transplantation (HSCT) is the only treatment known to slow or halt inflammatory demyelination among boys with the cerebral form of X-linked adrenoleukodystrophy (cALD), a devastating childhood condition affecting the central nervous system. HSCT can lead to a range of adverse outcomes including fatality. Previous studies have examined the potential predictors of post-HSCT survival and neurologic functioning. However, little is known about patients' daily-life adaptive functional outcomes (i.e., ability to communicate, maintain social relationships, and independently execute tasks of daily living). The purpose of this retrospective cohort study was to identify which patient characteristics and treatment-related variables predict long-term adaptive function among the survivors of HSCT for cALD. Methods: We obtained caregiver ratings of adaptive functioning of 65 transplant survivors at an average of 4.6 years (range: 1.0–24.1 years) post-HSCT. Using linear regression with penalized maximum likelihood estimation, we modeled the relative contribution of pre-transplant neurocognitive test performance, MRI severity, transplant regimen, and length of time since transplant on patient adaptive functioning outcomes. Results: Higher radiographic disease severity and poorer performance on baseline neurocognitive tests requiring fine motor skills and visual perception were associated with inferior adaptive functioning after HSCT. Use of radiation during the transplant preparative regimen also predicted poorer adaptive outcomes. Interpretation: In addition to radiological disease severity, baseline neurocognitive test performance is associated with post-transplant adaptive functional outcomes. Neurocognitive measures may play an important role in prognostic counseling and post-transplant treatment planning for patients considering HSCT for cALD.