Although psychosocial stress is consistently described as a casual factor for psychosis, the role of recent stressful life events (SLEs) is inconclusive. Studies with subjects with psychosis risk syndrome (PRS), fail to show a large number of SLEs but suggest greater stress sensitivity in these populations. We evaluate the presence of recent SLEs and stress sensitivity, and their relationship with symptoms and functionality in a sample consisting exclusively of help-seeking children and adolescents. Seventy-two 10- to 17-year-old help-seeking subjects who met PRS criteria and forty-two healthy control (HC) subjects participated in a naturalistic multi-site study. Measures of stress included the Stressful Life Events Schedule (SLES) and the G4 item of the Scale for Prodromal Syndromes (SOPS) scale. Child and adolescent PRS subjects presented greater number of SLEs during the previous year, greater total accumulated stress, greater sensitivity to stress, and more impaired tolerance to normal stress than did HC subjects. Stress measures showed a relationship with positive and negative attenuated symptoms, clinical variables and functionality. Our results support the role of stress in the PRS status. It reinforces the suggested differences for clinical presentation of PRS in terms of age, highlighting the importance of gathering data on the under-18 population.