Purpose: In light of the increasing demand for accessible mental health resources and the specific challenges associated with engaging adolescents in traditional therapy, it is crucial to evaluate alternative interventions that empower parents to manage child behavior and enhance parental competency effectively for which there has been limited research. This study evaluates the effectiveness of a self-help parental guidance book in enhancing parents' sense of competency and reducing parent-reported child behavior problems. Methods: Utilizing an experimental design, this study involved a heterogeneous convenience sample of 128 parents across various regions of Israel. Participants were given a pretest and then randomly assigned to an experimental or control group. The treatment group read a self-help guidebook within 4 weeks of the pretest after which both groups were then re-assessed using a post-test one month later. The "Me as a Parent" and "TOPSE Child Behavior Scales" measured parental sense of competency, and the "Disruptive Behavior Disorders Rating Scale" assessed the frequency of child disruptive behaviors as perceived by parents. Data analysis was conducted using regression analyses. Results: Parents who engaged with the self-help book reported significant improvements in parental competency and a reduction in child behavior symptoms compared to the control group. Regression analyses confirmed the book’s positive impact, highlighting substantial effect sizes (Cohen’s d = 0.68 for parental competency and Cohen’s d = 0.63 for reduction in child behavior symptoms). The analysis found that while the frequency and number of strategies used by parents did not predict a greater change in reducing behavioral problems, it did predict an increase in parents' sense of competency. Specifically, using strategies more frequently was linked to a higher general sense of competency (measured by MaaPS) and a sense of competency specifically related to discipline (measured by TOPSE). A greater sense of control (also measured by TOPSE) was observed with an increase in the number of strategies used. Implications: These results underscore the potential of self-help resources as effective tools for parental education in behavior management. The substantial effect sizes indicate that structured, self-administered guidance can significantly and substantively benefit parenting practices and outcomes. This study supports the broader implementation of such interventions, particularly in settings where traditional therapeutic resources are scarce or inaccessible. Future research should further explore the long-term effects of these interventions and the specific elements that most effectively boost parental efficacy and child behavior modification.