Systematic observations of 231 children (infancy to 5 years) and the 231 adults accompanying them were made in 29 supermarkets in Edmonton, Alberta, Canada. The objective of the study was to describe the influence of two indices of adult supervision in supermarkets on children's activities in shopping carts. Adult supervision was measured by whether the adult ever lost sight of the child and whether the adult was 10 feet or more from the child at any time during a shopping trip. 23% of the children stood on the ends or sides of carts; 49% climbed or tried to climb out of carts. Adults lost sight of a child, whether in or outside the cart, a mean of 3.3 times and were 10 feet away 2.7 times during an average shopping trip. Logistic regression showed that a child rather than an adult pushing a shopping cart through the store was the strongest factor related to standing on ends or sides of carts. Pushing by a child was more likely to occur when adult monitoring was low and when children were older. Climbing out was predicted by the number of times an adult was > or = 10 feet away, older children, and a child being in the cart basket as opposed to outside the cart or in the child safety seat.