Swedish preschool pedagogues have recently been coping with increased expectations to engage in “adult-led, goal oriented” teaching, and work with sustainability-related issues. In Swedish preschool provision, teaching and sustainability are contested concepts that embody pedagogical tensions (e.g. teaching as a school-like vs. a holistic activity; sustainability as an environmental and/or social concern). Some pedagogues have thus responded with ambivalence to this teaching/sustainability assignment. The present study explores how Swedish preschool pedagogues, experienced in Early Childhood Education and Care for Sustainability (ECECfS) research and practice, engage in teaching. Qualitative case studies were conducted of teacher teams from three preschools. The teams participated in a series of government-sponsored workshops for designing outdoor spaces in preschools as sustainable, multifunctional environments. Case studies were based on group interviews, surveys, and field observations. Drawing on concepts from cultural-historical activity theory, thematic analyses were conducted to characterize practitioner conceptions and practices of ECECfS and teaching in preschool. The study met all criteria for ethical conduct. Teachers described ECECfS in terms of what is learned and how. What: environmental knowledge; attitudes, feelings toward the environment, and toward others; self-confidence. How: arrangements for time “in nature”; systematic observation; pretend play; themed project work. Pedagogical tensions were identified which linked these descriptions thematically: ECECfS as teaching content vs. “teaching” values; approach vs. sensitivity to the environment; ECECfS as environmentally vs. socially focused. Implications are discussed for developing pedagogies that advance the ECECfS ethos of adult-child coparticipation in and co-determination of preschool activities.