Robust development of behavior change interventions is based on a sound understanding of the target group, the target behaviors that need to change, the context in which change will occur, the hypothesized mechanisms of change, and the behavior change techniques. Intervention development frameworks advocate a systematic approach to behavior change intervention development. Key tasks include (1) identify and analyze the problem addressed in behavioral terms; (2) identify intervention mechanisms, content, and delivery mode(s) and design a logic model or program theory; (3) develop materials or prototypes (e.g., interface); and (4) test the intervention iteratively through empirical optimization. The tasks apply to both developing new interventions and optimizing existing interventions. The tasks may differ somewhat for digital behavior change interventions (e.g., iterative testing and refinement of early prototypes during development). Depending on time and resources, the tasks can be completed relatively quickly or take considerable time. The current chapter presents key challenges in intervention development and describes potential solutions. Fidelity, feasibility, and acceptability should be considered during all development tasks. The chapter also provides recommendations for advancing the methodology of intervention development and the use of intervention development frameworks and approaches in practice and policy settings.

Motivational interviewing (MI) is a method of eliciting individuals’ inner motivation to change their behavior. MI is typically delivered within health care settings as well as in occupational and educational settings and in multiple populations. MI builds on practice skills that are relational and technical, aiming to evoke and reinforce client utterances in the direction of behavior change, termed change talk, and to reduce client utterances in the direction of maintaining current behaviors, termed sustain talk. Meta-analyses show that MI training leads to increased practice of relational and technical skills, and practice of relational and technical skills are related to change talk. Technical skills increase the proportion of change talk in relation to sustain talk. Sustain talk has a negative effect on behavioral outcomes, but change talk has a positive effect on behavioral outcomes. Meta-analyses also show positive effects of MI over six months in reducing or eliminating binge drinking, alcohol consumption, problematic substance use, and smoking, and increasing physical activity in chronic illness patients. Studies have shown positive effects of MI on behavior change in a range of behaviors and populations. A step-by-step guide to MI outlines typical intervention content, target populations and behaviors, practitioner training and skills required, and evaluation of fidelity and effectiveness.