The 15-minute city has recently gained attention as a planning approach by promoting active mobility through proximity to essential amenities. Existing literature has predominantly focused on dense urban cores and commuting patterns, frequently neglecting peripheral contexts and non-mandatory travel. This thesis addresses these subjects by investigating the determinants of mode choice in “Vila Franca de Xira”, a suburban municipality in the Lisbon Metropolitan Area. Based on an in-person intercept survey of more than a thousand respondents conducted in May 2025, the research adopts an advanced discrete choice modelling approach to analyse travel behaviour. The study compares a traditional Multinomial Logit (MNL) model with a more complex Hybrid Choice Model (or ICLV - Integrated Choice and Latent Variable Model).