Dynamical processes in molecules like bond shaking, breaking or making c- monlytakeplaceonatimescalefromthepico-downtothefemtosecondrange. Theadventofequallyfastlasersourcesandreal-timeobservationschemeslike pump-probe spectroscopy has facilitated the direct insight into such processes wheninitiatedbylight. Inparallelthedevelopmentofadvancedcomputational methods treating the dynamics of photoexcited molecular systems allowed a convergence between theoretical description and experimental observation of such ultrafast dynamical processes. Consequently, the idea emerged, not only to analyze, but also to control molecular dynamics in real time by adequately designed light ?elds. Stimulated by theoretical concepts for in?uencing the motion of molecular wave packets by means of simple few-parameter elect- magnetic ?eld sequences, experiments were driven toward a practical reali- tion of arbitrarily shaped laser pulses. This development culminated in the active feedback control of even complex systems. In addition this o?ers the unique possibility not only to determine the outcome of chemical reactions, butalsotoretrievespeci?cinformationaboutthechosendynamicalpathways, that is, to perform analysis by control. This book illustrates a vital research ?eld by covering a broad spectrum of molecular systems with growing complexity while demonstrating at the same time the convergence of experimental and theoretical approaches. After a g- eral introduction in Chapter 1, Chapter 2 starts with small isolated molecules in the unperturbed environment of the gas phase and Chapter 3 proceeds to more complex systems, but still in vacuum. A higher level of complexity is then reached in Chapter 4 where small molecules in a rare gas matrices are discussed serving as prototypeexamples for condensed phase dynamics.