Tufts/CfA/MIT Cosmology Seminar, at Tufts: Rob Crittenden, Princeton University Title: CMB Anisotropies from Cosmic Defects Abstract: Anisotropies of the microwave background present a crucial and unambiguous test for theories of the origin of structure. However, in a large class of models, known as cosmic defects, predictions for the anisotropies are complicated by the non-linear evolution of the fields. I will discuss the present state of calculations of the CMB anisotropies from cosmic strings and cosmic texture, focusing in particular on the existence of the so-called ``Doppler peaks".