Young offenders have numerous problems, including increased psychopathology, housing, and psycho-social stresses and increased rates of substance abuse. The current study investigated the contribution that substance use might make to a particularly vulnerable group of young people. Of the 300 young people approached for the study, 23.7% reported a prior suicide attempt. For this group, the most significant predictors of a prior suicide attempt were negative affect, prior exposure to violence, and housing stress. Life-time substance-use variables were most predictive of the number of suicide attempts a young person might make. Self-reported lethality (the expectation that on the last attempt the young person expected to die) was not strongly predicted by any variable. The research identifies the important role that dynamic risk factors (such as mood, substance use, and psychosocial stressors) play in increasing the risk of self-harm for young offenders, and raises the need to provide for more comprehensive discharge planning and support in order to manage these needs.