Introduction Managers play a key role in success of the organizations and performance of their employees. For instance, replacing a low performing manager with one that is a top 10% performer substantially improves team output (Lazear et al. 2015) and leadership explains between 14% and 45% of organizational success (Day and Lord, 1988; Joyce et al., 2003). Besides affecting performance, managers contribute to their subordinates’ well-being. Under good management, subordinates report higher job satisfaction (Bratt et al. 2000); take fewer sick days (Kuoppala et al., 2008); and report lower levels of burnout (Stordeur et al., 2001). However, research shows that 50% of managers fail at their job, resulting in their resignation. In part, this leadership derailment stems from inadequate selection and development of managers. Even though characteristics such as personality and cognitive ability predict managerial performance, standardized questionnaires and tests are rarely used in managerial selection, due to their poor face validity. Furthermore, most leadership development programs fail as they do not focus on measuring and improving important leadership behaviors. One way to improve managerial selection and development would be to focus on individual characteristics that a) predict job performance over and above cognitive ability and personality; b) can be assessed using methods of high face validity; c) can be developed through targeted interventions. We propose that the characteristic that fits all of these criteria is job knowledge, specifically procedural knowledge in the domain of leadership. Measures of job knowledge predict work performance over and above cognitive ability, have higher face validity and most HR professionals are extremely interested in developing and validating these measures (Schmidt and Hunter, 1998; Beier et al., 2018; Ryan and Ployhart, 2014). Furthermore, methods for assessing job knowledge such as situational judgment tests (SJTs), have substantial criterion validity. In recent years, there has also been more emphasis on the construct validity of SJTs and a construct-based approach in developing them. In line with the above, our main goal was to examine the role of procedural knowledge in predicting managerial success in the context of integrated model of leadership (DeRue et al., 2011). Integrated model of leadership proposes that different leader characteristics (e.g. personality, knowledge) predict leadership outcomes via different leader behavioral stlyes (e.g. transformational leadership). We identified five key generic leadership competencies/behaviors (motivating subordinates, developing subordinates, teamwork management, relationship management and decision-making) and developed a SJT to measure the procedural knowledge that underlines these competencies. We proposed that managers’ procedural knowledge, would predict additional variance in managerial work performance over and above other characteristics and that their behavior style would mediate the relationship between procedural knowledge and work performance. Methodology: We conducted two studies on samples of managers (N = 166 and N= 215) and their immediate subordinates (N = 238 and N = 662). Managers completed an SJT and a battery of self-report measures to assess their cognitive ability, personality, actively open-minded thinking, political skill and declarative knowledge of leadership as conceptualized by our competency model. In Study 1, we also asked them to rate their leadership behavior according to our competency model. Meanwhile, the subordinates rated their managers’ transformational leadership style (both studies) as well as their behavior according to our competency model (Study 2). They also reported their own work engagement, perceived organizational support and psychological safety, which we used as managerial work performance criteria. Results: To test our hypotheses, we conducted correlational analyses, multilevel regression and mediation analyses. Results showed that the managers’ procedural knowledge (expressed as the total score in the SJT) was not significantly related to work engagement and perceived organizational support of subordinates in neither study. However, it was positively related to psychological safety and explained an additional 5.5% of the variance of this criterion over and above other characteristics (Study 2). We found no evidence that leadership style has a mediating role between procedural knowledge (expressed as the total score in the SJT) and job performance. However, supplementary analyses showed that procedural knowledge in the domain of decision-making was positively related to psychological safety of subordinates through the managers’ leadership style in this domain. Furthermore, procedural knowledge in the domain of motivating subordinates was positively related to subordinates’ work engagement through transformational leadership. Contrary to our expectation, procedural knowledge in the domain of relationship management was negatively related to perceived organizational support and psychological safety of subordinates through the managers’ leadership style in this domain, but it had a positive direct effect on psychological safety. Conclusion: In conclusion, the findings of our research on the role of procedural knowledge in explaining the performance of managers are mixed. Our findings point to the value of using specific domains of procedural knowledge rather than assessing procedural knowledge of leadership as a whole. Furthermore, this paper contributes to the literature in the field of leadership by placing procedural knowledge as a characteristic within an integrated model of leadership and using a construct-based approach to measuring procedural knowledge with an SJT.