This paper has three main contributions to the debate about the value of management practices. First, the empirical confirmation of a strong and significant relationship between the level of management practices and three major dimensions of firms' performance (profitability, growth and productivity). The value of this contribution is grounded on a survey of 124 companies in a focused and careful choice of context: packaging industry in an emerging country, Brazil. Second, our theoretical conceptualization of management practices as capabilities addresses recent criticism of the Resource-based Theory and suggests there is no need for a new theory as the proposed Practice-based View. The third main contribution relates to the factors that affect the development of management practices. We confirmed that larger firms tend to have higher levels of management practices, although no support was found for the influence of another factor, the family ownership. We also identified that managerial hubris can be seen as a new strong factor negatively affecting the development of higher levels of management practices. Finally, the findings of this paper can bring attention to management as a new, internal component of the so-called Custo Brasil (Brazilian Cost) and its practical effect on the competitiveness of the Brazilian firms.