This bulletin first compares the proportion of Québec youth aged 15 to 24 who have had sexual intercourse at least once against youth in other provinces with the same characteristic, by age and sex, based on data from the 2009–2010 cycle of the Canadian Community Health Survey. This is followed by analyses of sexually active youth in Québec. The focus is on the number of sexual partners and the use of contraceptive methods such as condoms and the pill. In the second section, data from 2009–2010 are compared with those from 2003 to see if the sexual behaviours of youth changed during the 2000s. It then looks at the age at first sexual intercourse among youth by sex, number of sexual partners and contraceptive use. Finally, results for youth diagnosed with STIs by age at first sexual intercourse are presented for the 2009–2010 cycle only.