The purpose of this study is to examine factors affecting prisoners’ disciplinary misconduct and obtain solutions to rectify the problem of disciplinary infractions in Thai prisons. A multiple regression analysis was employed to examine data from a sample of 202 prisoners conveniently selected from 434 disciplinary violators in Thailand’s Nakhon Pathom Central Prison. Preliminary findings based on a bivariate correlation analysis examining the relationships between the independent factors and the level of disciplinary infractions in prison revealed four factors significantly related to the level of disciplinary misconduct, including classification of prisoners, association and learning, rational decision making, and low self-control. However, results from a multiple regression analysis found that rational decision making, and low self-control were the only two factors that were statistically significant. This finding supports the rational choice theory and self-control theory. To solve the disciplinary misconduct problem, prisons are recommended to improve measures of checking and employing harsher penalties. Additionally, policy recommendations to address prison overcrowding to facilitate the prevention of disciplinary misconduct were also discussed.