Despite hundreds of laboratory-based studies, very few researchers have investigated differences in spatial ability in large-scale, real-world settings. Laboratory-scale studies have found individual differences based on sex or gender, mathematical ability, nervousness, and previous experience. This study of 978 military college students tested whether the types of differences found in earlier laboratory studies would be found in a large-scale wayfinding task involving compass and map orienteering. Participants were required to find at least 8 of 10 points in a 4 h time period while covering about 6 km of woodland terrain. The results indicate that earlier laboratory findings are generally replicated for the large-scale task. Sex, previous experience, mathematical ability, and map-use skills were all found to be significant predictors of wayfinding performance.