High school dropout is commonly seen as the result of a long-term process of failure and disengagement. As useful as it is, this view has obscured the heterogeneity of pathways leading to dropout. Research suggests, for instance, that some students leave school not as a result of protracted difficulties but in response to situations that emerge late in their schooling careers, such as health problems or severe peer victimization. Conversely, others with a history of early difficulties persevere when their circumstances improve during high school. Thus, an adequate understanding of why and when students drop out requires a consideration of both long-term vulnerabilities and proximal disruptive events and contingencies. The goal of this review is to integrate long-term and immediate determinants of dropout by proposing a stress process, life course model of dropout. This model is also helpful for understanding how the determinants of dropout vary across socioeconomic conditions and geographical and historical contexts. There have been repeated calls in the scientific literature to consider high school dropout not as an event but as a process (see Christenson & Thurlow, 2004;Rumberger, 2011). In this view, dropout is the endpoint of a long trajectory of disengagement starting as soon as, and even before, children enter school. This long-term approach has led to breakthroughs in our understanding of the roots of dropout. Longitudinal studies spanning the first two decades of life have illuminated the role that early family circumstances and school experiences play in putting some children on a high-risk trajectory for dropout (e. Beechum, 2014). Understanding the causes of dropout among students who do not follow a clearly identified pathway out of school is necessary to tailor interventions to their needs (Feinstein & Peck, 2008). Among these dropouts, precipitating factors (i.e., situations emerging for high school students not long before the decision to dropout is made) could play an important role (e.g., see Bowers & Sprott, 2012b; America's Promise Alliance, 2014).In addition, even among students already considered at risk when they enter high school, there is considerable heterogeneity in terms of timing and outcomes, with some leaving school later than others and others unexpectedly graduating (Bowers, Sprott, & Taff, 2013;Vitaro, Larocque, Janosz, & Tremblay, 2001). This heterogeneity could be determined in part by circumstances emerging late in students' schooling careers. In fact, improved circumstances in adolescence can close wide achievement gaps established during the elementary school years (Dobbie & Fryer, 2011). Conversely, peak vulnerability could arise when early failure intersects with challenging circumstances in high school, such as when students are under important stress or are offered new opportunities incompatible with schooling (e.g., a full-time job). Attention to such precipitating factors among students following a recognizable long-term problematic path could contribute to a ...