Purpose: Successful business cooperation requires the managerial effectiveness shaped by capabilities necessary to leverage a firm's resources in the international marketplace. Because firms like other organisations can face unique challenges through building their managerial capabilities, the purpose of this study is to analyse managers' competencies of small-to-medium-sized firms and determine what the primary determinant of shaping managers' effectiveness is? Approach/Methodology/Design: A grounded theory and interviews with 142 Polish managers from private firms to determine their key competencies. Findings: The competencies categories emerged from the research findings. The study showed a dominant area of conceptual and relationship competencies in an entrepreneurial competency framework, which results from openness to the environment. Besides, this study confirmed other researchers' arguments that managerial competencies are thought to be multidimensional constructs. Practical Implications: The article brings several valuable information that can be the base material and reference to further research and practice. Originality/Value: The study combines research on business in Western countries with companies' activity from Central Europe. It fits into the research stream of competencies as drivers of managerial effectiveness, entrepreneurship, and an entrepreneurial competency framework.

Zbyslaw Dobrowolski Et Al (2021). Managerial Effectiveness in the Perspective of Competencies Towards Uniformity in Family Business, European Research Studies Journal Volume XXIV Issue 2, 227-237