<p><?noindent??>Source separation of waste is considered a crucial and fundamental step in waste management, which requires both the awareness and the active involvement of citizens.</p><p><?noindent??>This quasi-experimental study, based on the Theory of Planned Behavior (TPB), evaluated the impact of an educational intervention on waste separation practices among 100 housewives in Qom, Iran (50 in the intervention group and 50 in the control group).</p><p><?noindent??>Participants completed a validated 35-item TPB-based questionnaire at baseline and one month post-intervention. The intervention consisted of face-to-face training, educational pamphlets, instructional videos, and daily text messages targeting TPB constructs (attitude, subjective norms, perceived behavioral control, moral obligation, intention, and behavior).</p><p><?noindent??>Data were analyzed at two time points: baseline and one month post-intervention, using SPSS version 27 software. Of the 100 participants, 20 were single and 80 were married. Average scores for various constructs improved after the educational intervention: attitude (from 49.42 to 50.73), subjective norms (59.60 to 63.90), perceived behavior control (38.44 to 41.67), moral obligation (82.93 to 89.67), intention (83.40 to 92.80), and behavior (81.00 to 85.53). Significant differences between the groups were found in all constructs of the model after the intervention (<i>p</i> &lt; 0.05).</p><p><?noindent??>This study demonstrates the effectiveness of a theory-based educational intervention in promoting household waste separation behavior among women in a developing country context, offering practical implications for municipal waste management programs.</p>