Due to entrenched debate among affective scientists over the structure of affect, mixed emotions have received far less scientific attention than other emotional experiences. To address this gap in the literature, my dissertation makes theoretical and methodological contributions to the study of mixed emotions, defined here as the subjective experience of simultaneous positive and negative emotion (e.g., bittersweet feelings, nostalgia). The first aim of my dissertation was to develop a new perspective on mixed emotions that is not rooted in solving the current debate over structure of affect. To do this, I present a new, personalized perspective on mixed emotions in Chapter 1. I appeal to affective scientists to move past this debate to advance understanding of the subjective experience of mixed emotions and emphasize the importance of assessing both state and trait emotions (e.g., momentary emotions, general levels of affect) alongside state and “trait” context (e.g., physical location, culture). I present three methodological approaches that I believe will be valuable in building a new mixed emotions literature—inductive research methods, idiographic models of emotional experiences, and empirical assessment of emotion-eliciting contexts.The second aim of my dissertation was to develop a methodologically rigorous approach to studying mixed emotions that will allow researchers to begin building more sophisticated theories of emotion. Across two studies, I explored the frequency and nature of mixed emotions. Importantly, neither study was designed to address whether it is possible for people to experience mixed emotions. Instead, I used atheoretical scales which allowed participants to indicate mixed emotions if and when they occurred. Across Chapters 1 and 2, I found that approximately 20% of all image ratings were characterized by mixed emotions. Further, in Chapter 2 I found evidence for a category of images within the IAPS database that reliably elicited both positive and negative emotion. These results suggest that some IAPS images can be used to elicit low-intensity mixed emotions in laboratory studies and aid in characterizing problematic categories of IAPS images (i.e., neutral, erotic) and increase future researcher’s ability to design effective emotion elicitation paradigms. In Chapter 1, I argue that to better understand mixed emotions and build more sophisticated models of emotion, researchers must collect data across a variety of contexts. In Chapter 3, I explored whether the context of acute stress causes within-person changes in the structure of affect and frequency of mixed emotions. I used a traditional approach to capturing bipolarity in current mood alongside a novel method of testing bipolarity in response to affective stimuli. I failed to find consistent evidence for stress-related changes in the structure of affect or frequency of mixed emotions, however, future research is needed on this topic due to limitations associated with conducting online stress research during a global pandemic.