Strategic delegation is a widespread phenomenon in economic and social systems. In many situations the main interested party benefits from appointing a delegate to take action that the principal - were he playing - could not credibly take. This book contributes to the literature studying such a phenomenon, by extending the analysis of its implications for firms' strategy in product markets, by investigating how it may affect the trade union's activity, by studying its dynamic influence on the evolution of strategic interactions that the delegating party is involved in. The welfare effects of strategic delegation turn out to be uncertain and crucially depend on the features of the situation considered, both in static and in dynamic frameworks.