Abstract: The persistent trend of drug abuse among adolescents has become a public health concern across various regions, countries, continents and the world at large. Empirically, it has been ascertained that substance abuse is widespread globally with an estimated 120 million users of hard drugs such as cocaine, heroin and a host of other synthetic drugs. In 2013, drug use disorders resulted in 127,000 deaths up from 53,000 in 1990. Despite the efforts of National Drug Law Enforcement Agency (NDLEA) and other governmental agencies to stem the tide of substance abuse in Nigeria, there has been a consistent rapid rise in the number of cases of drug abuse among young people. In order to tackle the tenacious effects and the causes of prevalence, previous studies concentrated on different categories of people like drivers and artisans, while some focused more on both in and out-of-school adolescents; with little emphasis on factors determining drug abuse among in-school adolescents, particularly in Ido Local Government Area. This study, therefore, examined the social and psychological determinants of drug abuse among in-school adolescents in Ido Local Government Area of Oyo State, Nigeria.