The aim of this study was to investigate the validity of the Rotterdam Transition Profile (RTP) to describe the transition process from childhood to adulthood in young adults with cerebral palsy (CP). Participants were recruited from rehabilitation centres and hospital departments of rehabilitation. In total, 81 young adults (47 males, 34 females) with CP and normal intelligence participated (mean age 20y 5mo [SD 1y 4mo] range 18-22y; 95% spastic CP, 48% hemiplegia, 38% diplegia, 14% quadriplegia; 78% Gross Motor Function Classification System Level I, 83% Manual Ability Classification System Level I). The RTP and the Assessment of Life Habits questionnaire are used to measure transition and functioning in daily activities and participation. Almost all participants were in the transition process or had reached an independent adult lifestyle (ranging from 60-100%, housing 42%). Compared with able-bodied peers, young adults with CP lagged behind in their development in housing (25 vs 36%; p<0.05), employment (33 vs 49%; p<0.05), and intimate relationships (37 vs 76%; p<0.01). Associations were found between the phase of transition and age, parents' level of education, gross motor functioning, manual ability, level of education, and level of functioning in daily activities and participation. The RTP is a valid tool to gain more insight into the transition process, at the individual as well as at group level.