Corina Keller studies non-perturbative facets of abelian Chern-Simons theories. This is a refinement of the entirely perturbative approach to classical Chern-Simons theory via homotopy factorization algebras of observables that arise from the associated formal moduli problem describing deformations of flat principal bundles with connections over the spacetime manifold. The author shows that for theories with abelian group structure, this factorization algebra of classical observables comes naturally equipped with an action of the gauge group, which allows to encode non-perturbative effects in the classical observables. Contents Gauge Theory Differential Graded Algebras Differential Graded Lie Algebras and Derived Deformation Theory Factorization Algebras Equivariant Factorization Algebras from Abelian Chern-Simons Theory Target Groups Scientists and students in the field of mathematical physics, theoretical physics and especially mathematics with focus on homotopy theory and homological algebra About the Author Corina Keller currently is a doctoral student in the research group of Prof. Dr. Damien Calaque at the Université Montpellier, France. She is mostly interested in the mathematical study of field theories. Her master's thesis was supervised by PD Dr. Alessandro Valentino and Prof. Dr. Alberto Cattaneo at Zurich University, Switzerland.