Adolescence is a critical developmental stage and an opportunity to set a positive course for future health and well-being. Adolescence may be the "last best chance" to address some of the behaviors that can have significant repercussions for an individual's health trajectory, specifically the path to noncommunicable diseases (NCDs). Why should NCDs be discussed in a journal devoted to adolescent development? The World Health Organization (WHO) has identified four behavioral factors that account for at least half of the risk for these diseases--tobacco, excessive alcohol use, unhealthy diet or obesity, and sedentary lifestyle. And herein lies the connection to adolescents. Adolescents are typically healthy and only seek out sexual and reproductive health services. But adolescence is also when lifelong health behaviors are adopted. Two of the four modifiable risk factors--tobacco and alcohol--are most commonly initiated in adolescence. The other two risk factors--diet and exercise--could produce lifetime health benefits if adopted as positive behaviors in adolescence. Therefore, adolescence may be the last best chance to instill positive behaviors. By the "last best chance" the author means that adolescence is not necessarily the "best" chance, because it is good to build some of these positive behaviors, such as good nutrition, earlier in life. Nor is it the "only" chance, because people do try to improve their health behaviors later in life, albeit with more difficulty as by then these are often well-entrenched patterns. But adolescence is a window of opportunity. The broader health and development community must not adopt a "wait and see" mindset by failing to implement preventive health strategies that address risk factors for future morbidity and mortality patterns. While we must attend to the need for diagnosis and treatment of NCDs, working with adolescents provides a unique opportunity to prevent the wider spread of NCDs by cultivating protective factors.