Importance: Tobacco smoking is still responsible for more than 6 million preventable deaths annually, most of which occur in low- and middle-income countries. South American countries, Chile in particular, endure some of the highest cigarette smoking prevalence rates globally. Despite the lack of any meaningful increases in cigarette taxes (the most effective tobacco control measure) between 1999 and 2014, cigarette prices in Chile increased sharply almost entirely driven by British American Tobacco (BAT). Objective: To examine the associations between cigarette prices and nonprice tobacco control policies targeted at youth introduced in 2006 (Law 20105) and smoking onset among Chilean youths. Design, Setting, and Participants: This study used data from 8 waves of a large national school survey of urban communities in Chile conducted between October and December in 2001, 2003, 2015, 2007, 2009, 2011, 2013, and 2015 and discrete-time hazard models. Data analysis was performed from May 2017 to January 2019. Exposures: Prices, advertising, and retail restrictions. Main Outcomes and Measures: Smoking onset (the transition between never smoking and smoking) in youth. Results: In this study of 181624 survey respondents in 8751 Chilean secondary schools, higher prices (own-price elasticity [percentage change in quantity demanded in response to a 1% change in price], -0.40; 95% CI, -0.45 to -0.36) and the tobacco control policies enacted in 2006 (hazard ratio, 0.83; 95% CI, 0.81-0.85) were associated with lower hazards of starting smoking. The study found that an increase in real prices of 58.6% and the introduction of Law 20105 were associated with similar lower hazards of starting smoking (hazard ratio, 0.83; 95% CI, 0.81-0.85); in comparison, between 1999 and 2017, inflation-adjusted cigarette prices increased by 206%. Conclusions and Relevance: The findings suggest that higher prices initiated by BAT and the tobacco control policies enacted by the Ministry of Health in 2006 were associated with lower hazards of starting smoking in Chilean youth. Large cigarette tax increases may be a strategy that can be used to help reduce smoking among youths in Chile..