Long noncoding RNAs (lncRNAs) are increasingly recognized to contribute to cellular development via diverse mechanisms during both health and disease. Here, we highlight recent progress on the study of lncRNAs that function in the development of blood cells. We emphasize lncRNAs that regulate blood cell fates through epigenetic control of gene expression, an emerging theme among functional lncRNAs. Many of these noncoding genes and their targets become dysregulated during malignant hematopoiesis, directly implicating lncRNAs in blood cancers such as leukemia. In a few cases, dysregulation of an lncRNA alone leads to malignant hematopoiesis in a mouse model. Thus, lncRNAs may be not only useful as markers for the diagnosis and prognosis of cancers of the blood, but also as potential targets for novel therapies.