Thesis advisor: Mary E. Walsh / Non-academic factors significantly impact the achievement of students living in poverty (Ladd, 2012; Rothstein, 2010), with experts arguing for a systemic approach to address the complex factors associated with the growing opportunity gap (Bryk et al., 2010; Walsh & Murphy, 2003). In response, the integrated student support (ISS) model has emerged as one effective school-based method (Moore et al., 2017). Notably, both school social workers (SSWs) and school counselors are uniquely positioned to implement ISS models (Olsen, 2016; Teasley & Richard, 2017). School social work reflects a history of working primarily within the family and mental health domains, utilizing community partnerships to deliver intensive interventions to individual, at-risk students (Kelly et al., 2015a). Meanwhile, school counseling reflects a history of emphasizing the academic and social-emotional domains, utilizing individual, whole-school prevention and early intervention (Galassi & Akos, 2012). There is, however, little research on how these distinct professional histories influence systemic intervention implementation. Sequential explanatory mixed methods analyses examined how SSWs and school counselors implemented one systemic ISS model, City Connects, in high-poverty urban schools. Quantitative analyses examined the developmental domain (academic, mental health, family), intensity level (prevention/early, intensive intervention), and provider (school, community, Coordinator) of service referrals to determine differences depending on profession, while controlling for years of practice with City Connects and number of students served. Qualitative analyses bolstered quantitative findings. Post-hoc quantitative analyses further explored outcomes. Findings revealed no differences between school social workers’ and school counselors’ referrals across developmental domains, intensity levels, and service providers, irrespective of the number of years of practice and number of students served. Both professions believed the City Connects model increased the range of their responsibilities, impact on students, and satisfaction compared to their previous, more traditional roles. SSWs reported spending more time supporting families than school counselors in post-hoc analyses. Codified models of practice, like City Connects, may reduce potential practice differences associated with profession, develop and shift professional dispositions, encourage mindset shifts, and increase perceptions of increased impact and satisfaction. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental and Educational Psychology.