One of the big questions in developmental biology is: how do cells of the embryo get organized into tissues and organs? Organogenesis involves epithelial morphogenesis, a process where simple sheets of epithelial cells give rise to more complex 3D shapes. Development of skin appendages, organs that form as derivatives of the embryonic skin, is regulated by inductive tissue interactions between the ectodermal epithelium and the underlying mesenchyme. We use mammary glands and hair follicles as model organs to study epithelial morphogenesis. These organs develop though similar steps: initially a local thickening (called placode) forms concomitantly with specification and clustering of the underlying mesenchymal cells. Only at later stages becomes organ-specific morphogenesis (follicular downgrowth vs. branching) evident. We focus on two important morphogenetic processes: placode/mesenchymal condensate formation and mammary ductal invasion and branching morphogenesis.