One of the biggest and most important frontiers in nuclear theory today is to construct better and stronger bridges between bound state calculations and calculations in the continuum, especially elastic and inelastic scattering (reaction) theory, as well as teasing out the influence of the continuum on states near threshhold. This is particularly challenging as most many-body calculations are in a bound state formalism, while reaction calculations are more commonly in a few-body formalism. Furthermore many-body and few-body formalisms often use different language and emphasize different properties. To build better foundations for these bridges, we present an overview of bound state and continuum methods and, where possible, point to current and possible future connections. 4.2 Response functions and sum rules based on bound state techniques . . . . . . . . . 32 4.3 Double charge-exchange transitions and the double Gamow-Teller resonance from the shell model . .