Implementation research aims to narrow the "science to service gap" by addressing the challenges inherent in transferring research knowledge into practical real-world applications that improve people's lives. Ensuring that scientific findings bear fruit in terms of successfully employed service practices is not always an easy task. Implementation science has grown from an increasing awareness of the "science to service gap," i.e., concern about the often limited success of transferring research-based practices to ordinary service settings in fields as diverse as early childhood education, social services, mental health, employment services, or criminal justice. Awareness of this gap has inspired research efforts that deal with the challenges inherent in putting research knowledge into practice. Implementation research deals with the "what," "how," and "who" of implementation: What is to be implemented, how is the task to be carried out, and who will do it? Implementation is not a one-off event but an ongoing process from exploration through various stages to full implementation. Its ultimate aim is not just dissemination but sustainability beyond the initial implementation effort. This volume contains contributions looking at: - the implementation of treatment integrity procedures - defining and evaluating fidelity at the program level in psychosocial treatments - the effects of social support in the workplace on implementation outcomes - exploration-stage implementation variations and their effect on program cost-effectiveness - measuring implementation of a program on two levels simultaneously - the ecology of sustainable implementation