As limited-control dog parks become more popular, concerns arise about whether these parks encourage interdog aggression. Systematic observations made at 1 park over 72 hr across 8 months found that 28 conflicts or potential conflicts occurred (< 0.5%). Of these, 14 were clear aggressive episodes. Each lasted less than 1 min (< 0.33% of total observation time). There were 14 other incidents of possible aggression that were ambiguous in nature. Each lasted less than 30 sec (< 0.17%). None of these incidents led to serious injury. Of the 177 dogs observed, only 9 were aggressive toward other dogs (5%): 6 aggressors, once each; 2 aggressors, twice each; 1 aggressor, 3 times. Results indicate that aggression in limited-control dog parks may be relatively rare and probably presents only a limited risk to dogs and their caregivers (owners). In part, this may be because owners who frequent dog parks are self-selecting, self-monitoring, and self-limiting in regard to dog aggression.