The CSC intervention: A comprehensive universal internet-based intervention to prevent anxiety, depression, substance use, and related harms in Australian adolescents aged 13 to 16 years.

Australian school students in grade 8 and 9 (aged 13-14 years, 52.1% male) were assigned to one of four groups: (1) Climate Schools–Substance Use, focusing on substance use only; (2) Climate Schools–Mental Health, focusing on depression and anxiety only; (3) Climate Schools–Combined, focusing on the prevention of substance use, depression, and anxiety; or (4) active control. Interventions were delivered for 2 years. Dataset includes primary outcomes of knowledge related to alcohol, cannabis, and mental health; alcohol use, including heavy episodic drinking; and depression and anxiety symptoms at 12, 24, and 30 months after baseline.