Development of the vertebrate lung is a complex process involving the input of signaling pathways to coordinate the specification and differentiation of multiple cell types. The Wnt signaling pathway plays a critical role in the development of many vertebrate tissue types, including the lung. However, the functions of individual Wnt ligands during the specification and development of respiratory lineages have not been fully addressed. In this dissertation, I combine mouse genetic models and ex vivo tissue culture assays to determine the function of Wnt2 signaling in lung development. These studies reveal critical roles for Wnt2 signaling during the specification of lung progenitors in the foregut endoderm, and during airway smooth muscle development. These findings provide new insight into the position and contributions of Wnt signaling within the hierarchy of signaling pathways governing lung morphogenesis.