For the 17% to 26% of K-12 students who have a diagnosable psychological disorder, school is the primary access point for mental health services. In addition to psychosocial difficulties, students with internalizing problems display elevations in the stress hormone cortisol. While early intervention can help regulate cortisol levels (CL), over 80% of students with internalizing difficulties never receive therapeutic services. School psychologists can provide timely evidence-based interventions to bridge the gap between existing needs and available services using a multi-tiered problem-solving approach. This study examined psychosocial and biological effects of one such intervention—solution-focused brief therapy (SFBT)—on internalizing problems of four 8- to 9-year-old students in a public school. After a three-session SFBT intervention, teachers and students reported a significant reduction in student internalizing problems on the BASC-3 FMI (p < .05). Although only one student showed a robust decrease in salivary cortisol, the other three displayed dysregulated, attenuated morning cortisol levels (CL) which could have masked CL changes. Results generally supported the usefulness of SFBT in schools with students experiencing internalizing problems.