This month’s Views and Reviews focuses on different aspects of the diagnosis of mosaicism. The first piece was written by Treff and Marin, who discuss the methodologic challenges of preimplantation genetic testing for aneuploidies and how the diagnosis of “mosaic” has led to a significant reduction in the accuracy of such testing. The second article by Viotti et al. provides an excellent overview of outcome data from >1,000 mosaic embryo transfers. The investigators make a strong case for three categorizations of embryos: euploid, aneuploid, and mosaic, and that use of mosaic embryos will prevent the discard of embryos that may lead to live birth. The final piece in this series was written by Besser et al., who discussed the various society recommendations for genetic counseling and prenatal diagnostic testing after mosaic embryo transfer and question whether these are truly data-driven. This collection of pieces will give the reader a deeper understanding of the controversy and management of mosaic embryo transfer.