The Netherlands has dozens of disadvantaged neighbourhoods where residents lack the ‘collective efficacy’ to guard themselves against disorder and crime. A multitude of interventions are used to try to improve the situation, but it is unknown if these interventions work. This book is a so called ‘realist evaluation’ of interventions implemented by local organizations such as municipalities, housing corporations and police in order to make disadvantaged neighbourhoods more liveable and safe. As such, this book is intended to make clear which interventions are promising. A realist evaluation means that an hypothesis about the effectiveness of interventions that has been formulated on the basis of theory, is further sharpened (where needed) on the basis of empirical research (Tilley 2010). One of today's major criminological theories, is collective efficacy theory by Sampson et al. (1997). Drawing and improving on this theory we state that the collective efficacy of a neighbourhood is its residents capability to exercise informal social control on incidents of disorder and crime. This capability is based on the residents trust in each other and on their trust in professionals working for local organizations. Where there’s distrust, collective efficacy is weakened. This means that a improvement of a neighbourhoods liveability and safety calls for a strengthening of collective efficacy – which in the first place demands regaining trust. Our hypothesis about the strengthening of collective efficacy, is that residents trust can be regained because professionals - through their collaboration on interventions – exercise formal social control on incidents of disorder and crime. On the basis of their regained trust residents will subsequently be more willing and able to act against disorder and crime themselves. This theoretical reasoning of how interventions could have the foreseen effect, is followed by empirical research on their implementation in order to ascertain to what extent this effect actually can take place. To ...