Small and mid-sized cities (SMCs) are increasingly where people in Canada "live, work, and play" (Statistics Canada, 2022, 2023. In 2021, for example, eight of the top ten fastest growing Canadian census metropolitan areas were mid-sized cities-including Kelowna, Halifax, Guelph, and Moncton (Statistics Canada, 2021). There is a growing recognition that SMCs serve as repositories of innovation in urban theory and policy, offering distinct contexts for technology, culture, creativity, and collaboration, and potentially holding the key to Canada's collective well-being (e.g., Flatt, 2018; SDG Cities, 2021). SMCs, however, grapple with the global forces which channel resources to larger cities (Barber et al., 2023;Filion, 2023;Grant et al., 2019). "Slow growth," "shrinking," "less favoured," "peripheral," "intermediate," and "second tier" or "third tier" are all terms reflecting Canada's diverse urban geographies and are fundamentally about the broader socio-spatial and power relationships that disadvantage SMCs (e.g., Hall & Hall, 2008;Hartt, 2021). But not all SMCs' problems are the same, and neither are their successes. There is thus a critical need to think about the role of SMCs in building places, economies, and communities. This special section for Canadian Geographies/Géographies canadiennes examines some of the most pressing challenges facing SMCs in Canada, providing a conceptual framework for understanding these cities across the disciplinary boundaries of geography, planning, urban studies, and environmental sciences. Its impetus was a May 2022 summer school on SMCs in Victoriaville, Quebec. Organized by the Canadian Research Chair of small and mid-sized cities in transformation (at UQAM, Quebec) and the Adaptive Cities and Engagement Space (at Memorial University, Newfoundland and Labrador), this event emphasized the need for greater research collaboration on SMCs between different disciplines and among Canadian universities.We use the label "SMCs"-which in Canada generally refers to a vast and dynamic urban spectrum of cities with more than 10,000 and fewer than 500,000 residents-while foregrounding the limitations of such numeric definitions, following previous researchers (Bruneau, 2000;Hartt & Hollander, 2018; Seasons, 2003). For example, what commonalities exist between a population centre of 10,000 and a city approaching the ceiling of 500,000? Others, like Tassonyi (2017) stretch the upper limit of a Canadian mid-sized city to 2 million! There is enormous diversity even among cities in the same Département d'études urbaines et touristiques,