Emotions play an important role in human behavior, even more so in large congregations of people where emotional states are prompt to be contaged and amplified. This work presents a qualitative systematic review of the literature concerning the estimation of emotions and affects in real-life crowded environments, covering the aspects of methods and datasets. The academic search engine Scopus was inquired and the search was limited to publications in the English language addressing any of the aforementioned aspects. The aim of this contribution is to highlight advances, limitation and trends in addressing the estimation of emotions in crowds.