Substance Use of Homeless and Precariously Housed Youth in a Canadian Context Rick Csiernik 1 & Cheryl Forchuk 2 & Kristy Buccieri 3 & Jan Richardson 4 & Abraham Rudnick 5,6 & Laura Warner 7 & Amanda Wright 7 # Springer Science+Business Media New York 2016 Abstract Substance use is common among homeless and precariously housed youth, yet few longitudinal studies track their usage over time. This paper analyzes data from a study of 187 youth and reports on their substance usage in the preceding month, year, and over their lifetime. The results are compared within the sample by sex and against a sample of similarly located housed youth. Findings suggest that female homeless and precariously housed youth report lower substance use, but that with interventions substance use decreases for both sexes. Compared to housed youth, those who are homeless and precariously housed begin substance use at a significantly younger age. Keywords Addiction . Homelessness . Longitudinal . Sex . Precariously housed . Substance use . Youth Int J Ment Health Addiction DOI 10.1007/s11469-016-9656-4 * Rick Csiernik rcsierni@uwo.ca 1 School of Social Work, King’ s University College at Western University, 266 Epworth Avenue, London, ON N6A 2M3, Canada 2 Arthur Labatt Family School of Nursing, Western University, London, ON N6A 5B9, Canada 3 Department of Sociology, Trent University, Otonabee College, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada 4 Arthur Labatt Family School of Nursing, Western University, 151 Dundas St. 3rd floor, PO Box 5045, London, ON N6A 4L6, Canada 5 Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada 6 St Joseph’ s Healthcare, Hamilton, ON, Canada 7 Lawson Health Research Institute, 750 Baseline Road East, Suite 102, London, ON N6C 2R5, Canada