[영문]This paper is a response to trends in the evidence-based practice (EBP) movement that emphasizes evidence for interventions over evidence for assessment and treatment planning. I show the relevance of descriptive, non-experimental research to assessment and treatment planning, which are the foundations of effective practice. I also wanted to contribute to definitions of the term ‘evidence’ and to conceptualizations of clinical expertise and client concerns and preferences, all of which are underconceptualized in EBP and evidence-based medicine, which is the parent discipline of EBP. I have illustrated these points through my presentation of descriptive, non-experimental research on resilience, schema theory, gender studies and brain functioning, which I call the RSGB assessment and I have applied this assessment to practice with families whose children have emotional and behavioural issues. Thus, I have sought to show that effective interventions are not possible without an in-deep understanding of the persons and systems with whom we intervene.