This thesis is an investigation of self-regulatory and problem gambling behaviour. Although the inability to self-regulate has been identified as a key factor contributing to gambling problems (Baumeister, Heatherton, & Tice, 1994), little research has been conducted to understand the relationship between self-regulation and gambling. The aim of the dissertation research was to identify whether or not problem gamblers have less self-regulatory ability than do non-problem gamblers and, if so, which self-regulatory mechanisms break down for problem gamblers. In particular problem gamblers' ability to (a) implement discrepancy reduction skills (i.e., an inability to detect a discrepancy between one's goals and one's behaviour); (b) set goals; or (c) self-monitor were investigated. Study 1 was designed to investigate the relationship between self-regulatory ability and problem gambling behaviour. It was found that problem gamblers have less self-regulatory ability than do non-problem gamblers. As problem gambling scores increased, reported self-control scores decreased. Study 2 was designed to understand whether or not the ability to implement discrepancy reduction skills breaks down for problem gamblers when engaged in gambling behaviour. Problem gamblers who gambled persisted at an impossible tracing task for longer than did problem gamblers who did not gamble. Study 3 was designed to understand whether or not the ability to set appropriate goals plays a role in problem gambling. Results indicate that at-risk and problem gamblers may be underregulating because of goal fluctuation. That is, feeling an intense urge to gamble may result in more positive thinking about gambling and, subsequently, make it difficult to set appropriate gambling goals. Study 4 was designed to understand whether or not the ability to self-monitor plays a role in problem gambling. Participants reported lowered self-awareness while gambling. Problem gamblers also reported being in greater dissociative-like states while gambling.