Nigeria is the most populous country in sub-Saharan Africa. It also has a very young population. The majority of the population is below the age of 25 years, with 22 percent of the country s population between the ages of 10-19 years. Data on sexual and reproductive health (SRH) outcomes in Nigeria highlight the importance of focusing on adolescents. At 576 maternal deaths per 100,000 live births, Nigeria accounts for roughly 14 percent of the global burden of maternal mortality (DHS 2013/WHO 2014). Global evidence shows that young girls bear a higher burden of maternal mortality and morbidity. Data show that the average age at sexual debut is roughly 15 years of age among adolescent mothers in Nigeria (DHS 2003, 2008, 2013). This note presents the findings of a recent study on Nigeria that examines determinants of adolescent sexual behavior and fertility, with a narrower focus on knowledge, attitudes and behaviors of adolescents aged 10-19 years old in Karu Local Government Authority (LGA), a peri-urban area near the capital city of Abuja.