This study examined the dynamic and multi-level relationships among the Behavioral Inhibition System (BIS), negative affect and performance. Participants performed multiple trials of a simulated air traffic control task. A single measure of BIS was taken before practice, whereas negative affect and performance were measured at repeated intervals. As expected, there was a negative relationship between negative affect and performance at both an inter- and intraindividual level of analysis. The key findings from this research relate to dynamic effects. The detrimental effect of negative affect on task performance strengthened across practice, at both levels of analysis. The negative relationship between BIS and performance was also found to change over time. These findings are discussed by drawing on resource allocation theory and reinforcement sensitivity theory. This study emphasizes the importance of examining dynamic and multilevel relationships to understand how BIS and negative affect relate to task performance.