Active transportation, including walking and cycling, is a key strategy to reduce air pollution, traffic congestion, and improve public health. Despite numerous studies on active transportation choice, differences in travel behavior between mandatory and discretionary trips, as well as the combined effects of gender and occupation, have received limited attention. This study aims to identify and compare factors affecting active transportation choice for mandatory and discretionary trips while considering gender- and occupation-related differences. After removing incomplete records from the 2017 National Household Travel Survey (NHTS), 106,024 valid observations were analyzed using binary logistic regression models. The models were estimated based on gender and trip purpose (stage one) and gender and occupation type (stage two). Results indicate that although several factors, including greater use of public transportation, part-time employment, flexible working hours, and higher household income, increase the likelihood of choosing active transportation across most groups, the magnitude and significance of these effects vary among different population groups. Conversely, being a driver, having lower education, residing in lower-density areas, and owning more household vehicles reduce the probability of active transportation. Model evaluation using Akaike Information Criterion (AIC) and Area Under the ROC Curve (AUC) demonstrated satisfactory goodness of fit and predictive performance. The novelty of this study lies in its simultaneous analysis of the effects of trip purpose, gender, and occupation type on active transportation choice and in comparing behavioral patterns across these groups. The findings can assist planners and policymakers in developing targeted strategies to promote sustainable transportation based on the characteristics of different demographic and occupational groups. Although based on US data, the findings offer valuable insights for urban transportation planning and policy development in Iran due to similar urbanization trends and travel behavior.