Assessing and researching social work students’ skills prior to first placement presents challenges, but also the opportunity for comparison with students’ perceptions of their abilities/skills at an important professional development stage. This paper reports on initial quantitative results from a three-year study of students’ self-confidence in core skills/micro skills at the profession’s ‘Readiness for Direct Practice’ threshold in England. A combined cohort of postgraduate and undergraduate social work students (n = 95) at one university completed a three-stage integrated self/module-evaluation questionnaire during a common module. Using a Self-Assessed Skills Inventory (SASI), a self-efficacy scale based on Likert-scale responses to twenty-eight statements was developed and validated for internal consistency. Linear analysis of self-efficacy values, assessment outcome, programme level and prior work experience for a non-biased sample (n = 66) at the final stage shows results are independent of both programme level and prior experience. However, a correlation established between self-efficacy and marks for an assessed interview is shown to be strongly positive and significantly predictive for undergraduates, but weaker and negative for postgraduates. Considering relevant literature, the study’s limitations and implications for other social work programmes, this study establishes direct criterion-related validity between a self-efficacy scale and formal assessment.