Gender-based violence (GBV) against primary school girls represented a pervasive human rights violation and public health crisis undermining educational access, learning outcomes, physical health, and psychological well-being across Uganda. Despite constitutional guarantees of children's rights and government commitments to eliminating genderbased violence, girls in primary schools continued experiencing multiple forms of violence including sexual harassment, physical punishment, verbal abuse, early forced marriage, and sexual assault both within school premises and surrounding communities. Namayingo Town Council in Namayingo District, located along Uganda's border with Tanzania in the eastern region, faced particularly acute GBV challenges due to cultural practices condoning early marriage, poverty driving transactional relationships, fishing community dynamics facilitating exploitation, and limited protective infrastructure. Various stakeholders including government agencies, non-governmental organizations, schools, and community groups implemented interventions aimed at preventing and responding to GBV against girls. However, the effectiveness of these interventions remained inadequately documented, limiting evidencebased programming and resource allocation. This study investigated school-based interventions (safe spaces, life skills education, reporting mechanisms, teacher training, guidance and counseling) and community-based interventions (awareness campaigns, community dialogues, economic empowerment, local council engagement, traditional leader mobilization) to determine their effectiveness in preventing and responding to gender-based violence against primary school girls. The study employed a descriptive cross-sectional survey design with mixed methods approaches. The target population comprised 2,840 primary school girls in Primary 5-7, 180 teachers, 45 Parent-Teacher Association members, 12 Local Council leaders, and 8 NGO representatives in Namayingo Town Council. Using purposive and simple random sampling, 150 respondents were selected including 90 girls (Primary 5-7 students), 35 teachers, 15 PTA members, 6 Local Council leaders, and 4 NGO staff. Data collection employed semi-structured questionnaires for girls and teachers, key informant interview guides for stakeholders, focus group discussions with girls and parents, and document review of GBV incident records. The girls' questionnaire assessed GBV experiences, awareness of interventions, perceived effectiveness, utilization of services, and safety perceptions. Quantitative data were analyzed using SPSS version 26 generating frequencies, percentages, means, and cross-tabulations. Qualitative data were thematically analyzed identifying patterns in intervention effectiveness, implementation challenges, and protective factors. Ethical protocols included parental consent for minors, child-friendly research methods, psychological support referrals, and confidentiality protections. The study revealed high GBV prevalence with 67.8% of girls reporting experiencing at least one form of gender-based violence in the past year. Sexual harassment was most prevalent (43.3%), followed by physical punishment (38.9%), verbal abuse (36.7%), and unwanted touching (27.8%). School- based interventions showed moderate effectiveness overall (M=3.18, SD=0.84), with safe spaces (M=3.62, SD=0.78) and guidance counseling (M=3.45, SD=0.81) rated most effective, while reporting mechanisms (M=2.76, SD=0.94) showed limited effectiveness due to fear of retaliation and lack of confidentiality. Community-based interventions demonstrated similar moderate effectiveness (M=3.24, SD=0.79), with awareness campaigns (M=3.58, SD=0.76) and community dialogues (M=3.41, SD=0.83) receiving higher ratings than economic empowerment programs (M=2.84, SD=0.96) which reached limited beneficiaries. Girls who accessed both school and community interventions reported significantly lower victimization rates (32.4%) compared to those without intervention access (78.6%), suggesting combined approaches were most protective. However, implementation gaps included inadequate funding (cited by 82.9% of implementers), insufficient trained personnel (74.3%), cultural resistance (68.6%), and weak referral systems (71.4%). School- and community-based interventions demonstrated moderate effectiveness in preventing and responding to GBV against primary school girls in Namayingo Town Council, with potential for substantially greater impact if implementation challenges were addressed. Interventions providing safe spaces, education, awarenessraising, and supportive services showed promise, but effectiveness was constrained by resource limitations, inadequate coordination, cultural barriers, weak accountability mechanisms, and systemic gaps in protection systems. The most effective approaches combined multiple interventions across school and community settings, addressed both immediate protection and underlying risk factors, engaged multiple stakeholders including girls themselves, and maintained sustained rather than sporadic implementation. However, even the most effective interventions reached limited beneficiaries, leaving many girls unprotected. The study recommended that Namayingo District Local Government should establish a Multi-Sectoral GBV Prevention and Response Task Force coordinating stakeholder efforts; allocate dedicated budgets for GBV interventions with minimum 5% of education budgets supporting prevention programs; mandate comprehensive sexuality education and life skills training in all primary schools; establish functional GBV reporting and referral systems with trained focal persons in every school; strengthen economic empowerment programs targeting vulnerable families; enforce legal frameworks through prosecution of perpetrators; engage traditional and religious leaders as GBV prevention champions; and implement community accountability mechanisms monitoring intervention effectiveness and survivor support.