The framework of this research consists of eight quality management (QM) principles (customer focus, leadership, involvement of people, process approach, system approach to management, continual improvement, factual approach to decision-making and mutually beneficial supplier relationships) according to the ISO 9001 standard. The implementation of these principles results in QM practices often divided into infrastructure and core practices. The aim of this study is to investigate which infrastructure QM practice affects all core QM practices. The literature review leads to the assumption that implementation of employee involvement (as one of the infrastructure QM practices) might be crucial for the implementation of process approach, system approach to management, continual improvement and factual approach to decision-making (core QM practices). Empirical research was conducted on large-sized Croatian companies. The research instrument was a questionnaire addressed to the board of directors and quality managers. In order to reveal which infrastructure practice has an impact on core QM practices, multivariate analysis of variance was performed. Research results showed that employee involvement through different concepts (employee training, communication, empowerment and rewards and recognition) has a positive impact on the implementation of process approach, system approach to management, continual improvement and factual approach to decision-making.