Self-esteem, a person’s overall evaluation that she is valued and accepted vs. devalued and rejected by others, is crucial for people quality of life. As such, self-esteem has been central in the social-psychological literature since the late eighteenth century. However, its relevance is coupled with lack of agreement on how self-esteem is best conceived and assessed. Here we review definitions and measures of self-esteem in relation to quality of life in order (a) to understand how self-esteem has been defined, operationalized and assessed, and (b) to clarify which facets of self-esteem have been overlooked and need further study. Although we found multiple definitions of self-esteem, which led to a series of measures ranging from single item to multi-dimensional measures of state, trait and contingent self-esteem, the motivational component of self-esteem and its in-context behavioral correlates have yet to be operationalized. What follows, is that whether people think, feel, or behave in particular ways is caused by, concomitant with, or causes self-esteem, is still not understood. Because self-esteem is an emotionally laden system monitoring one’s relational value to others, we suggest that future research could use new technology-based research methods and eventually grasp real-time self-report and behavioral assessment of self-esteem. This appears a promising approach to overcome the limitations of self-esteem’s current theorizations and operationalizations. Thus, a new line of research considering the momentary experience of self-esteem, its behavioral components and its social context, could potentially unveil novel processes and mechanisms linking self-esteem and quality of life that have yet to be discovered and understood.