The confirmation that there is a positive relationship between leadership style and organizational performance is no unanimity in the field, but most researches emphasizes that transformational, collaborative and participatory leaders are critical to the success of an organization. To examine the question this dissertation analyzes the influence of leadership style on the decisions made during the life cycle of an organization considering: (a) the organizational life cycles, (b) the characteristics of leadership that decision makers have and express, and (c) performance indicators. A longitudinal study was carried out by combining a qualitative and quantitative approach to analyze two small Rio de Janeiro family businesses in the retail trade, chosen according to convenience and accessibility. The selected cases focused on companies in their maturing stage according to Greiner s model (1998) which we reapplied questionnaires designed from the situational leadership pillars of Bass (1990) and based on the questions of Pillai et al. (1999). The conclusions were that there is a positive relationship between leadership style of the decision maker and performance, and that the transformational leadership of the company B on average generated better results than the company A with a transactional leadership. Finally, the study also suggests that a transformational leadership style that overlaps a transactional leadership one, seems to be a differential to the organizational results.