This volume contains the proceedings of the third conference on Parametric Optimization and Related Topics, held in Guestrow from 30 August until 5 September, 1991. Parametric optimization, as a part of mathematical programming, investigates the behaviour of solutions to optimization problems under data pertubations. This behaviour, like continuity and differentiability, plays a fundamental role for a series of further questions that are of interest from a practical as well as a theoretical point of view. Many relations to other disciplines of operations research, like stochastic programming, modelbuilding, numerical methods, multiobjective optimization and optimal control, originate from this behaviour. The presented articles (all refereed) are topical and original papers reflecting recent results to current directions of research in theory and applications.