By looking at the existence of homogeneous subgroups of psychotic-like experiences with similar trajectories and their association with established risk factors such as a family history of mental illness, substance use, and childhood victimisation it is hoped to elucidate a clearer picture of the development of psychosis. *Demographics of developmental trajectories of psychosis (1) Do developmental trajectories exist for psychotic-like experiences being reported at 11.6, 13, 14, and 16.5 years via the PLIKS (interview)? (2) Are parental histories of mental illness and substance use disorder, adverse events during pregnancy, and socio-economic variables able to differentiate between the trajectories? * Trauma-based antecedents of the developmental trajectories of psychosis. (1) When adjusting for IQ and early childhood psychotic disorders, do childhood adversities (such as bullying, death of relative or friend, and emotional cruelty) predict any of the psychosis trajectories? (2) When adjusting for IQ, early childhood psychotic disorders and childhood adversities, do parental childhood adversities (up to the age of 17) predict any of the psychosis trajectories? (3) Are there significant associations with any of the trajectories when entering time-varying exposure variables into the model, such as social skills, substance use, schizotypy, attachment and moods? *Outcomes and risk profiles for the developmental trajectories of psychosis (1) What sort of outcomes are associated with each trajectory? (2) When concentrating on the worst outcome trajectory, what risk profile can be identified and what does that elucidate regarding underlying mechanisms and treatment strategies?