Objective: Young people who are at clinical high risk (CHR) of developing psychosis are often help seeking and have significant distress and dysfunction. There are limited guidelines for the assessment and treatment for this population. The aim of this guideline was to develop treatment recommendations for this at-risk group. Method: A systematic search was conducted for published guidelines for CHR. All current guidelines for schizophrenia were reviewed for treatment guidelines on individuals at CHR. The recommendations adopted were primarily drawn from the European Psychiatric Association (EPA) guidance on the early intervention in clinical high-risk states of psychoses and the 2014 National Institute for Health and Care Excellence (NICE) guidelines on the treatment and management of those at CHR for psychosis. Results: After the guideline development process described, 9 recommendations were developed based on the quality of evidence, appropriateness for the Canadian health care system, and clinical expert consensus. Conclusions: Assessment by an expert in the field was the first recommendation. It was recommended that treatment follow a staged approach with psychological treatments being the first-line treatment and pharmacotherapy reserved for adults, those who did not respond to psychological interventions, and those who had more severe symptoms.