Lifeguards are instructed to respond both to dangerous behavior and to distress/drowning events. Variability in lifeguard effectiveness may result from variability in how individual lifeguards define what events are important to monitor (“critical events”). The variability in defining critical events was examined in the current study by presenting videos of normal aquatic activity to lifeguards (N=17), lifeguard instructors (N=10), non-lifeguards (N=20), and students enrolled in a lifeguarding course (N=12). Participants were asked to identify the events that they thought were important for a lifeguard to monitor and provide an explanation as to why they were critical. All participant groups (instructors included) had very few events that were consistently reported, and many of the events that the instructors or lifeguards reported were also well-reported by non-lifeguards. These results suggest that there is a lack of agreement in the identification of critical events.