Suicide is a potentially preventable public health issue. It is therefore important to examine its immediate precursors, including suicidal ideation and attempts, to help in the development of future public health interventions. The present study reports the prevalence of suicidal ideation and attempts in the past 12 months in children and adolescents and identifies correlates of such behaviors in a large and diverse sample of middle and high school students. Data were drawn from a representative sample of Ottawa students (n=1922) aged 11–20 years (14.4±1.9 years) from three cycles (2009, 2011 and 2013) of the Ontario Student Drug Use and Health Survey (OSDUHS), a cross-sectional school-based appraisal of students in grades 7–12 across Ontario, Canada. Overall, 10.8% of students exhibited suicidal ideation and 3.0% reported suicide attempts in the past 12 months. The conditional probability of making an attempt was 25.5% among suicide ideators. Multivariable analyses indicated that being a girl and using alcohol and cannabis were positively associated with suicidal ideation, while tobacco was positively associated with suicide attempts. Being a victim of school bullying was significantly associated with reports of suicidal ideation and attempts, whereas school connectedness had protective effects against both suicidal ideation and attempts. These results indicate that suicidal ideation and attempts are related to other risky behaviors. Suicide-prevention efforts should be integrated within broader health-promoting initiatives.