Introduction Behavior change techniques (BCTs) are considered as active components of implementation strate‑ gies, infuencing determinants and, ultimately, implementation performance. In our... Show moreIntroduction Behavior change techniques (BCTs) are considered as active components of implementation strate‑ gies, infuencing determinants and, ultimately, implementation performance. In our previous Delphi study, experts formulated ‘implementation hypotheses’, detailing how specifc combinations of BCTs and strategies (referred to as BCT-strategy combinations) might infuence determinants and guideline implementation within youth care. For example, educational meetings providing instructions on guideline use were hypothesized to enhance practition‑ ers’ knowledge and, consequently, guideline implementation. However, these hypotheses have not been verifed in practice yet. Method We conducted a cross-sectional study involving practitioners and management professionals from youth (health)care organizations. Using questionnaires, we obtained data on the presence of BCT-strategy combinations and their perceived infuence on determinants and implementation performance. Chi-squared tests and regres‑ sion analyses were employed to determine the infuence of specifc BCT-strategy combinations on determinants and implementation performance. Results Our analyses included data from 104 practitioners and 34 management professionals. Most of the manage‑ ment professionals indicated that the BCT-strategy combinations positively infuenced or had the potential to infu‑ ence their implementation performance. At the practitioner level, half of the combinations were perceived to have a positive infuence on determinants and implementation performance. Furthermore, practitioners who reported the absence of BCT-strategy combinations were more skeptical about their potential infuence on determinants and implementation performance. Conclusion Several BCT-strategy combinations were perceived to improve or potentially improve implementation performance of both practitioners and management professionals. In the development and evaluation of imple‑ mentation eforts, we advocate for clearly describing the implementation efort’s objective and using frameworks that detail the BCTs inducing behavior change, the strategy employed, and the processes driving the observed changes. Understanding these interconnected processes is important in designing targeted, evidence-based Show less