Background: Several common health issues frequently occur in Islamic boarding schools. Among the most common are scabies, shortness of breath, fever, fainting, coughs and colds accompanied by the flu, gastritis, and others. Scabies, also known as “gudik,” is a common skin disease among children, particularly in densely populated areas. Students living in Islamic boarding schools seem “bound” to experience this itchy condition, characterized by intense itching, skin rashes, and scratches. Personal hygiene, knowledge, and support from teachers and peers are among the contributing factors. Objective: This study aims to analyze the influence of personal factors (knowledge and self-efficacy) and environmental factors (social support, access to supplies, and observational learning) on the incidence of scabies, with personal hygiene practices serving as a mediating variable. Methods: This quantitative study used a cross-sectional design and was conducted at three Islamic boarding schools in the Lowokwaru subdistrict of Malang City. Sampling was performed using a multistage stratified random sampling technique, with 274 students selected from a total of 728 students. Results: The study shows the influence of environmental factors—comprising social support (p-value = 0.006) and ownership of supplies (p-value = 0.000)—on personal hygiene practices. Meanwhile, among personal factors, only self-efficacy had a significant effect (p-value = 0.000) on personal hygiene practices. The two factors that simultaneously influence personal hygiene practices are self-efficacy (p-value = 0.000) and ownership of personal hygiene supplies (p-value = 0.000). However, neither personal nor environmental factors had an effect on the incidence of scabies with personal hygiene practices as a mediating variable (p-value = 0.05). Conclusions: There is no effect of environmental and personal factors on the incidence of scabies among boarding school students, with personal hygiene practices serving as a mediating variable, at boarding schools in Lowokwaru Subdistrict, Malang City.