Background: The neural crest is a transient embryonic stem cell population. Hypoxia inducible factor (HIF)-2α is associated with neural crest stem cell appearance and aggressiveness in tumors. However, little is known about its role in normal neural crest development. Results: Here, we show that HIF-2α is expressed in trunk neural crest cells of human, murine, and avian embryos. Knockdown as well as overexpression of HIF-2α in vivo causes developmental delays, induces proliferation, and selfrenewal capacity of neural crest cells while decreasing the proportion of neural crest cells that migrate ventrally to sympathoadrenal sites. Reflecting the in vivo phenotype, transcriptome changes after loss of HIF-2α reveal enrichment of genes associated with cancer, invasion, epithelial-to-mesenchymal transition, and growth arrest. Conclusions: Taken together, these results suggest that expression levels of HIF-2α must be strictly controlled during normal trunk neural crest development and that dysregulated levels affects several important features connected to stemness, migration, and development. K E Y W O R D S embryogenesis, HIF-2α, migration, neural crest, stem cells, trunk neural crest Camilla U. Niklasson and Elina Fredlund contributed equally to this work.