Increased standardization within adolescent literacy education leads to dehumanization of students who become a demographic label, statistic, or problem to fix (Blackburn, 2013; Freire, 1996; Gordon, 2009; Paris & Alim, 2017; Paris & Winn, 2013). This is particularly true in urban contexts where cultural and linguistic diversities are essentialized, viewed as neutral, or erased from the curriculum (Alim & Paris, 2017; Alvermann, 2011b; Christenbury, Bomer, & Smagorinsky, 2011; Gadsden & Dixon-Roman, 2016; Gutierrez & Penuel, 2014), responses that neglect the impact of culture on learning (Hollins, 2015). This study uses a humanizing, critical ethnographic perspective (Paris & Winn, 2013; Street, 1984) and participant observer methods (Spradley, 1980) to investigate the adolescent literacy instructional practices at an urban Catholic high school. Catholic schools have historically been sites of academic achievement for students from marginalized groups, demonstrating opportunity and potential for highly effective adolescent literacy practices (Gabert, 1973; Greeley, 1982; Horning, 2013). Using a critical sociocultural theoretical orientation (Moje, Lewis, Encisco, 2007) and culturally sustaining pedagogies (Paris, 2012; Paris & Alim 2014, 2017) as a framework, this research asked the questions: How does the framework of culturally sustaining pedagogies inform teachers' understandings of effective literacy instruction in a religious high school? and What practices are highly effective urban religious school teachers using to support adolescent students' literacy achievement? Findings provide localized information to support adolescent literacies instruction and leadership at the urban Catholic school site, expand the body of literature surrounding culturally sustaining pedagogies, and complicate understandings of highly effective literacy instruction in an era of increasingly standardized schooling.