The current analyses of observational data found that oncoming traffic substantially affected driver stopping patterns and turn signal use at the target stop sign. The percentage of legal stops and turn signal use by drivers in the presence and absence of traffic was analyzed using a multi-element design. The results showed that legal stops were completed 100% of the time when oncoming traffic was present compared to 4.6% of the time when oncoming traffic was absent. Additionally, drivers' used turn signals 63% of the time when oncoming traffic was present compared 43.7% of the time when oncoming traffic was absent. Detailed analyses of these data suggest that researchers should consider traffic conditions when conducting similar observational research in the area of driver safety.