This paper provides the results of an analysis conducted to assess the safety impact of an integrated vehicle-based crash warning system based on naturalistic driving data collected from a field operational test. The system incorporates four functions that warn the driver of an imminent rearend crash, excessive speed to an upcoming curve, lane-change crash, or unintentional lane departure. The safety impact is assessed in terms of observed changes in driving behavior, exposure to driving conflicts, near-crash experience, and projected potential reductions in the number of annual target crashes. Unintended consequences are examined by analyzing driver engagement in secondary tasks and eyes-off-the-forward-scene behavior. A total of 108 subjects, split by gender and three age groups, participated in the field test by driving in an unrestricted manner for a period of six weeks each. In the first two weeks, designated as the baseline period, the subjects performed their naturalistic driving with the system turned off while the data acquisition system collected their performance data. In the last four weeks, designated as the treatment period, the system was turned on and provided the subjects with visual, auditory, and haptic crash warning signals. This paper discusses the safety impact of the system for individual subject groups based on gender and age. The integrated system has the potential to reduce the number of rear-end, oppositedirection, lane-change, and road-departure crashes involving at least one passenger car. Moreover, the system did not influence drivers to engage in more secondary tasks.