Valence is central to the experience of emotion. However, to the detriment of affective science, it is often ill-defined and poorly operationalized. Being more precise about what is meant by valence would make for more readily comparable emotion stimuli, methodologies, and results, and would promote consideration of the diversity, complexity, and function of discrete emotions. This brief review uses prior literature and an informal survey of affective scientists to illustrate disagreements in conceptualizing valence. Next, we describe issues of valence in affective science, particularly as they pertain to the emotion process, the functions of emotion, and precision in empirical research. We conclude by providing recommendations for the future of valence in affective science.