The ability to accurately recognize facial expressions is a key element of social interaction. Facial emotion recognition (FER) assessments show promise as a clinical screening and therapeutic tool, but realizing this potential requires better understanding of the stability of this skill. Transient mood states are known to bias emotion recognition in some contexts and may represent a critical factor impacting FER ability. In particular, it is unclear how natural fluctuations in individuals' mood state over time contribute to specific changes in the ability to recognize facial expressions. The current study tested 55 neurotypical participants across multiple visits using the Emotion Recognition test and found that fluctuations in positive and negative mood state altered recognition of specific emotions. Surprisingly, effects of mood state on emotion recognition were noncongruent; increased positive mood was associated with improved recognition of scared expressions but worsened recognition of happy expressions. Our results suggest that minor fluctuations in mood state in a neurotypical population affect emotion recognition. Therefore, mood should be taken into account by researchers and clinicians assessing FER skills. (PsycInfo Database Record (c) 2021 APA, all rights reserved).