This study documents the process of implementation of an adolescent reading intervention. Using data from observations of teachers (n=17) during the 2013-14 school year, I conducted a nuanced descriptive analysis of fidelity of implementation (FoI). I also analyzed weekly logs completed by literacy coaches (n=3) to examine variation in quantity and intensity of coaching. I then compared variation in coaching with variation in FoI, and finally compared FoI to outcomes for students (n=287). FoI at observation 1 was found to predict coaching time, and FoI across both observations predicted student outcomes, emphasizing the critical role of implementation in intervention research.