At times, it may be desirable to determine that a client system is, or to determine the number of client systems that are, presenting particular dynamic content when an auditable event occurs in the dynamic content. One manner of making the determination may include accessing presentation time information that indicates the time(s) at which one or more client systems present particular dynamic content and accessing event time information indicating the time(s) at which one or more auditable events occur in the dynamic particular content. Based on the presentation time information and the event time information, it may be possible to determine that a client system is, or to determine the number of client systems that are, presenting particular dynamic content when an auditable event occurs in the dynamic content.