Appropriate supervision is recommended as a strategy to prevent pediatric farm injuries, yet virtually nothing is known about the quality of adult supervision on farms. We therefore explored the nature of adult supervision among pediatric farm injury cases using three theoretically relevant dimensions of supervision: (1) attention, (2) proximity, and (3) continuity. We examined a retrospective case series of 334 pediatric farm injury cases from Canada and the United States that resulted in death or required hospitalization. Patterns of supervision were coded according to the three dimensions. Approximately two-thirds of the injured children (231/334; 69%) had an adult supervisor available (attention). The supervisor was in close proximity of the child in only about half the cases (169/334; 51%) and it was even less common for the supervision to be continuous (37%). Thus, many injuries occurred when children were inadequately supervised. However, approximately one-third of the injured children (112/334; 34%) had what in other circumstances would be considered adequate adult supervision at the time of their injury event, defined theoretically as having supervision available, proximal, and continuous. Yet, children on farms were injured even in the presence of adequate adult supervision. These findings, along with a growing body of literature examining pediatric farm injuries, suggest a need to develop a new definition of adequate adult supervision within the context of the agricultural work environment, or to consider restricting the access of children, especially the very young, to this hazardous worksite.