The purpose of this quantitative study was to explore the influence of protection motivation theory (PMT) constructs on security behaviors of undergraduate students. More specifically, the primary focus of this study is to answer our primary research question: to what extent do the independent variables (perceived threat severity, perceived threat vulnerability, self-efficacy, response efficacy, and response cost) explain undergraduate students' employment of smartphone security measures? The smartphone security measures studied are: changing password, using an antivirus app, backing up data, and using unsecured Wi-Fi in public places. The research literature on smartphone security practices of undergraduate students indicates that demographic factors (such as age, gender, and class) influence smartphone security practices of undergraduate students. Additionally, PMT factors (which include perceived threat severity, perceived threat vulnerability, self-efficacy, response efficacy, and response cost) are primarily applied to health-related studies and have been adopted for general computer security research of students; however, there is scant literature with regards to how PMT can be applied to smartphone security practices of undergraduate students. The selected method of research for this study employed a quantitative, nonexperimental approach using an existing survey instrument. The target population was undergraduate college students: the sample population was 200 randomly selected students. The sample contained 58% female and 42% male respondents evenly distributed across class. Analysis of the model was performed using negative binomial regression. Although all hypotheses were not supported by the analysis, the following were found to be significantly predictive of smartphone users: self-efficacy showed a statistically positive association with changing passwords, perceived threat vulnerability, and self-efficacy showed a statistically positive significant association with using antivirus apps, and self-efficacy showed a statistically positive association with backing up data. However, none of the constructs showed a statistically significant association with using unsecured Wi-Fi in public places. The practical implications of the research are for industry to focus on better design of antivirus apps to protect users, and to increase self-efficacy among smartphone undergraduate users through training and education. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]