Transportation plays a key role in urban sustainability planning and urban greenhouse gas emission reductions. Globally, cities have established sustainability agendas and policies to guide the shift from traditional private automobile dependent transportation systems towards an increased use of public transportation, cycling, and walking. While the surrounding physical urban form and governance structures condition public transportation services, there are also many other factors to consider when discussing sustainability. As such, comprehensive planning and policy-oriented assessment frameworks that are independent of local conditions are still largely missing in literature. This paper presents a Public Transportation Sustainability Indicator List (PTSIL) that provides a platform for an integrated assessment of environmental, economic, and social dimensions of sustainability through an indicator-based approach. To demonstrate its use, the PTSIL is applied to analyze the policy documents of public transportation agencies in Helsinki, Finland, and Toronto, Canada. The results show that while both cities achieve relatively high scores in all dimensions, there is still high variability among individual indicators. The PTSIL presents a missed stepping stone between descriptive definitions of transportation sustainability and case specific sustainability performance assessments, offering an opportunity within the planning and policy-making sectors to review, assess, and develop public transportation services comprehensively.