Little is known about kindergarten students' active school transportation (AST) and stroller/wagon use as sedentary travel devices. The primary objective of this cross-sectional study was to determine the prevalence of kindergarten children arriving to school by active and sedentary modes, including strollers, in Toronto elementary schools and compare to students in kindergarten to grade 6 (K–6). The secondary objective was to examine factors associated with AST in kindergarten and K–6 students. School travel mode was counted using direct observations at elementary schools in the City of Toronto in 2015. Two samples were observed: 1) Kindergarten sample: a random sample of schools with separate kindergarten entrances (n = 26 schools, 1069 children); 2) Kindergarten to grade 6 sample: observations were conducted at arrival locations at 50% of eligible elementary schools for students of all ages (n = 88 schools, 17,224 children). Proportions arriving by different travel modes were compared using Chi-square analysis. Negative binomial regression was conducted to examine the association between school characteristics and AST. AST was lower in the kindergarten compared to the K–6 sample (60% versus 74%, χ2 = 91.37, p < 0.001). The predominant sedentary mode for kindergarten students was by vehicle (38%), with < 2% using strollers/wagons. Recent immigrant status was related to higher AST in kindergarten students; higher social disadvantage, crossing guards, school population and collision rates were related to higher AST in the K–6 sample. Factors influencing AST in young students require further investigation to influence the development of healthy active lifestyles at an early age.