Over the past decade, microRNA‐142 (miR‐142) is emerging as a major regulator of cell fate decision in the hematopoietic system. However, miR‐142 is expressed in many other tissues, and recent evidence suggests that it may play a more pleiotropic role during embryonic development. In addition, miR‐142 has been shown to play important functions in disease. miR‐142 displays a functional role in cancer, virus infection, inflammation, and immune tolerance. Both a guide strand (miR‐142‐3p) and passenger strand (miR‐142‐5p) are generated from the miR‐142 hairpin. miR‐142‐3p and ‐5p display overlapping but also independent target genes. Loss of function mouse models (genetrap, global knock out [KO], and conditional KO) have been reported and support the important role of miR‐142 in different biological processes. This review will summarize the abundant literature already available for miR‐142 and will lay the foundation for future works on this important microRNA. Developmental Dynamics 246:285–290, 2017. © 2016 Wiley Periodicals, Inc.