Purpose: The article critically reflects on the issue of age in workforces in human resource management and related fields. Age is widely used by scholars to denote the entire workforce of a company. The vast remit of this concept has resulted in many ongoing debates, such as young vs. old employees, mature employees, the aging workforce, as well as various stereotypes pertaining to age in academic research.

Methodology: The paper reviews recent academic literature: articles from peer-reviewed journals, written in English, and published in 2000–2018. Keywords and elimination criteria are explained in the corresponding section.

Findings: Research in this field shows the use of inhomogeneous groups in accordance to their age, which ultimately threatens to hinder the comparability of undertaken studies in this domain.

Research implications: There exists no clear consensus regarding the age-markers or barriers used to distinguish the workforce of an organization or to form groups of employees of a given age-cluster.

Originality: This text is the first review of studies in the field, in which age has been the main criterion to distinguish workforce. The review encourages dialog among scholars from various disciplines as a way to lessen discrepant categorizations.