This chapter provides an overview of the neurocognitive, behavioral and developmental aspects of the neurofibromatosis type 1 (NF1) phenotype. Investigations into the pathogenesis of cognitive dysfunction are also presented, with a focus on human neuroimaging studies and mouse models. These studies have provided major insights into the molecular and biochemical abnormalities associated with NF1 that impact on cognitive performance. Preclinical studies suggest that pharmacological correction of these abnormalities has the potential to normalize aspects of the NF1 cognitive phenotype. These are reviewed along with the rationale for ongoing and future human clinical trials.