Background: Primary dysmenorrhea, characterized by painful menstrual cramps without underlying gynecological pathology, affects a significant proportion of adolescent girls, leading to school absenteeism and reduced quality of life. Nonpharmacological interventions offer safe alternatives to manage this condition, yet awareness among adolescents remains limited. Objective: This study evaluated the effectiveness of a structured teaching program (STP) on knowledge regarding non-pharmacological management of primary dysmenorrhea among adolescent girls in selected government girls’ high schools in Kamrup (Metro) District, Assam. Methods: A pre-experimental study with a one-group pre-test-post-test design was conducted among 60 adolescent girls aged 13–16 years from two government girls’ high schools. A structured questionnaire assessed knowledge before and after a 45- minute STP. Data were analyzed using paired t-tests and chi-square tests to evaluate knowledge improvement and associations with socio-demographic variables. Results: The mean pre-test knowledge score was 12.3 ± 3.2, which increased significantly to 22.7 ± 2.8 post-intervention (p < 0.001). Significant associations were found between pre-test knowledge and age (p = 0.02), educational status (p = 0.04), and age at menarche (p = 0.03). Conclusion: The STP significantly enhanced knowledge of non-pharmacological management strategies, suggesting its potential as an educational tool to empower adolescent girls in managing primary dysmenorrhea.