Background: Ambulances are where patient care is often initiated or maintained, but this setting poses safety risks for paramedics. Paramedics have found that in order to optimize patient care, they must compromise their own safety by standing unsecured in a moving ambulance. Hypothesis/Problem: This study sought to compare the quality of chest compressions in the two positions they can be delivered within an ambulance. Methods: A randomized, counterbalanced study was carried out with 24 paramedic students. Simulated chest compressions were performed in a stationary ambulance on a cardiopulmonary resuscitation (CPR) manikin for two minutes from either: (A) an unsecured standing position, or (B) a seated secured position. Participants' attitudes toward the effectiveness of the two positions were evaluated. Results: The mean total number of chest compressions was not significantly different standing unsecured (220; SD = 12) as compared to seated and secured (224; SD = 21). There was no significant difference in mean compression rate standing unsecured (110 compressions per minute; SD = 6) as compared to seated and secured (113 compressions per minute; SD = 10). Chest compressions performed in the unsecured standing position yielded a significantly greater mean depth (52 mm; SD = 6) than did seated secured (26 mm; SD = 7; P < .001). Additionally, the standing unsecured position produced a significantly higher percentage (83%; SD = 21) for the number of correct compressions, as compared to the seated secured position (8%; SD = 17; P < .001). Participants also believed that chest compressions delivered when standing were more effective than those delivered when seated. Conclusions: The quality of chest compressions delivered from a seated and secured position is inferior to those delivered from an unsecured standing position. There is a need to consider how training, technologies, and ambulance design can impact the quality of chest compressions.