This paper explores the development and implementation of strategies for sustainable mobility in Basel, Switzerland. Basel (Bâle, Basilea, Basle) has been identified as a ‘relatively successful’ practitioner of sustainable mobility, with an urban form that is not only conducive to walking and cycling, but also has an extensive public transport system and high levels of commuting using these sustainable modes of transport. With a low share of journeys by motor vehicles compared to many other European cities – combined with a legally‐binding objective to reduce vehicle traffic by a further 10% from 2010 to 2020 – Basel appears to be a forerunner with regard to sustainable mobility policy and practice. Five years after this objective was passed into law – following a public vote, as Basel is part of the Swiss confederation and practices direct democracy – this study aims to assess the extent of policy implementation and reflect on challenges and opportunities for the future. The paper presents findings from a series of interviews with stakeholders in Basel on the theme of sustainable mobility. Key questions include: is it possible to develop coherent strategies and policies to further reduce the role of motor vehicles and in doing so, achieve a modal shift? How does participation in a direct democracy influence strategy and policy development and outcomes? Do compromises and trade‐offs mean strategies and policies promoting sustainable mobility are, like Swiss cheese, riddled with holes? By illustrating challenges and opportunities when advancing sustainable mobility in a participative culture, the study provides insights for policymakers and researchers in other contexts. Among the conclusions is an emphasis on the importance of committed individuals capable of expanding the ‘strategy space’ of processes. Participation provides one such opportunity, yet may also generate divergent or contradictory trends causing incrementalism. A rapid transition to sustainable mobility is thus likely to require increased politicisation of the topic by both politicians and civil servants.