This article is on alcohol and drug abuse as predictors of risk taking behaviour among secondary school students in Kajiado North Sub-County. The area has numerous drug and alcohol ecological factors that could influence the behaviour of adolescents. Since the area is home to a lot of the working population of the adjacent Nairobi City County, people from various backgrounds have immigrated there. As such, the societal values held by the inhabitants of the area are not easy to define. In this context, adolescents are prone to indulge in drug and alcohol abuse that could impact their lives negatively. This is particulars o since it alcohol and drug abuse encourages unprotected sex among students and by extension abortion, gang behaviour as students look for money to sustain the risky behaviours among others. The arguments of this article are guided by the ecological Systems Theory. Information is obtained from a descriptive survey of 267 students and 15 principals that was I undertook in 2017. The sample was obtained using stratified proportionate sampling and total population sampling techniques in the 15 public secondary schools in Kajiado North Sub-County. Data from students was collected using questionnaires while the principals were interviewed. The findings show that alcohol and drug abuse risk-taking behaviour in adolescents are higher in the wake of poor family stability, negative peer influence, breakdown of societal values and weak government measures. As such, it is recommended that it is important to ensure that cohesiveness in the families is encouraged so as to reduce alcohol and drug abuse behaviours among students. Teachers should also be at the forefront for checking alcohol and drug abuse in schools so as to protect the spread of risky taking behaviours among peers. Members of the society who sell alcohol to students should be identified and punished as per the existing law. The government should strengthen its programs (in schools and in the mass media) to guide students on the dangers associated with alcohol and drug abuse among students. This article is organized into Introduction, Literature Review and discussions.