Working on What Works (WOWW) is a manualized, 10-week classroom intervention based on solution-focused brief therapy. This study evaluates WOWW using a randomized experimental, posttest-only design. The study included 30 fourth and fifth grade classrooms, containing 30 teachers and 413 students. Results indicate no significant differences between WOWW and control groups for student internalizing and externalizing behaviors, studentteacher relationships, student academic performance, or teacher sense of efficacy. However, students in the WOWW group had significantly fewer days absent from school compared with the control group. Additionally, teachers' ratings on WOWW classrooms' performance improved significantly more than teachers' ratings on the control classrooms. Results from this study show that WOWW is a feasible intervention for therapists to use in schools and can be implemented across classrooms in both public and private schools. WOWW has potential to improve student attendance and classroom performance, both of which are important areas of concern for schools. Schools are important places for family therapists to address the growing mental health needs of children because school systems are often the primary provider of mental health services to families (Metcalf, 2013; Vennum & Vennum, 2013). However, families of children with mental health needs frequently see these needs go unmet, a likelihood that increases with the severity of the conditions and the poverty of the children (Ganz & Tendulkar, 2006). Unmet mental health needs have been linked to a variety of educational concerns, including behavioral, emotional, and attendance problems (Butler & Lynn Platt, 2007; Jaffee et al., 2005; The White House, 2013). All of these issues impact the academic performance of children and adolescents making it important for marriage and family therapists (MFTs) to intervene in school systems. Rones and Hoagwood (2000) define school mental health as any program or intervention delivered in a school setting aimed at improving students behavioral, emotional, or social functioning. Within the field of school-based mental health, MFTs fill a role that applies a family systems perspective to educational systems and act as a vital part of collaborative mental health teams in schools (Laundy, 2015). Some systems thinkers suggest that in order to thrive and to make the greatest contributions to mental health the MFT field needs to develop theories and techniques that are uniquely relevant to systems other than the family such as schools (Terry, 2002). This