Distracted driving is a major public safety concern, contributing an average of 21,000 crashes annually in Massachusetts alone. This thesis aims to provide an improved understanding of drivers’ cell phone use prevalence and the related safety impacts. Specifically, this thesis includes: 1) an analysis of data collected in two direct observational studies carried out in 2011 and 2012; 2) an evaluation of the collection methods employed for direct observation studies; and 3) an analysis of distracted driving crashes from 2007 to 2011 in Massachusetts. The two observational studies resulted in a sample of 61,096 drivers from 305 different locations, resulting in an average cell phone usage rate to be 6.4 percent, with a handheld usage rate of 5.3 percent and a text messaging usage rate of 1.1 percent. Teens were observed text messaging more often than adults and elders, while the handheld conversation rate was similar for both teens and adults. Drivers observed wearing seat belts had a lower cell phone use than those who were not wearing seat belts. A second study was conducted to investigate limitations of the direct observation of drivers’ cell phone use, specifically involving the influence of intersections and observers. Twelve observations were conducted using a combination of observers and video data collection. The study found that at signalized intersections the drivers’ text messaging rate was higher, and it is suggested that for future observations another category for cell phone use is used to separate text messaging while stopped. Lastly, the crash data analysis was completed, and within the five years analyzed there were a total 628,495 crashes and 17 percent of overall crashes that involved distracted driving. The rate of distracted driving is inversely proportional to speed, weather severity, and road conditions, as when the preserved danger increases the rate of distracted driving crashes decreases. There was a relationship between the observed cell phone use and the rate of distracted driving crashes with females and teens having both the highest cell phone use rate and the highest rate of distracted driving crashes. The completion of research tasks within the framework of this thesis achieved the overall objective of providing insight on drivers’ cell phone use and crash data statistics across driver demographics, road types, and times of day. Moving forward the insights established within this thesis may prove useful in the establishment of targeted and specific countermeasures.