Neurofibromatosis type 1 is a common autosomal dominant disorder in which affected children and adults develop both benign and malignant tumors. In addition to tumor formation, children with neurofibromatosis type 1 may exhibit specific learning disabilities, distinctive bony abnormalities, and hyperpigmented lesions (cafe-au-lait macules, skinfold freckling, and Lisch nodules). With the identification of the neurofibromatosis 1 gene in 1990, significant strides have been made towards elucidating the pathogenesis of specific clinical problems in neurofibromatosis type 1 and developing first-generation, biologically based targeted therapies. Recent advances in mouse modeling have likewise yielded important insights into the genetic and cellular mechanisms underlying neurofibromatosis 1-associated tumor formation and learning disabilities. This review will focus on the clinical features of neurofibromatosis type 1, the molecular biology of the neurofibromatosis 1 gene, and the use of mouse modeling to recapitulate the human condition.