Many social interventions do not lend themselves easily to impact evaluation. A successful impact assessment of a relatively simple linear cause-effect relationship is at best not a straightforward matter. Most policy interventions are, however, typically complex organisational and institutional programmes that have ambitious multi-sectoral transformation agendas. Such complex interventions make life even more difficult for the evaluator who wishes to conduct an impact assessment. Unlike the everyday examples of instantaneous linear impact, the impact of social programmes is often only evident after some time has lapsed. It is usually the accumulated result of various effects or outcomes that together produce the benefits to the target group. Moreover, it is made up of very different kinds of mutually reinforcing effects and often at different levels. Subsequently, they normally comprise of various potentially overlapping and cumulat