The study of early avian evolution—how birds evolved from dinosaurs and radiated into the most diverse group of amniotes on the planet—is one of the most dynamic areas of research in paleontology, fueled not only by the rapid rate of discovery of new specimens (see Foth et al.; Musser and Clarke; and Xing et al.) and sheer volume of available material (see Zheng et al.) but also by the innovative application of new analytical methods to key evolutionary questions (see Heers et al.; Liu et al.). Also critical to our understanding is the exceptional level of preservation of many Mesozoic and early Cenozoic bird fossils, which not uncommonly preserve soft tissues and other indicators that may provide key insights into the biology of these organisms (see articles by Clark and O’Connor; Foth et al.; Xing et al.; Zheng et al.). In putting together this research topic, our aim was to further expand our understanding of early avian evolution by gathering a body of work highlighting the diversity of research currently being undertaken in this area. As such, articles published in this topic have augmented our understanding of a variety of important areas related to early avian evolution, including the recognition of new taxonomic diversity (see Clark and O’Connor and Musser and Clarke), insights into the evolution of key avian traits such as flight (Heers et al.) and a toothless beak (see Louchart et al. and Zheng et al.), and the piecemeal evolution of crown avian biology (see Atterholt et al. and Heers et al.).