This study evaluates the personal values profile, leadership styles, leadership effectiveness, and their relationships with organizational differentiation among 400 Brazilian executives from 48 organizations. A closed instrument was developed to assess personal values, while existing instruments were used to evaluate leadership styles and effectiveness. Linear regression was used to analyze the relationships between personal values balance and leadership effectiveness, as well as between personal values balance and organizational differentiation. The Organizational Differentiation Model (ODM) was applied to compute the organizational differentiation index (ODI) for each organization. The study found that executives have an unbalanced personal values profile, with a predominance of economic and theoretical values. Leadership styles were found to be inflexible, with selling and sharing ideas as dominant styles. Leadership effectiveness was at a moderate level. The study revealed a high positive relationship between personal values balance and leadership effectiveness, as well as between both variables and organizational differentiation. Values are crucial in leadership, influencing perceptions of appropriate ends and means. The study highlights the importance of values in shaping behavior and leadership effectiveness. The research also emphasizes the need for leaders to be responsible, people-centered, and coherent in their actions. The study recommends a critical analysis of personal values in leadership development to ensure a comprehensive understanding of values and their impact on leadership and organizational effectiveness. It also suggests the need for democratizing leadership to make it accessible to all, and for future research to explore leadership styles and effectiveness in larger and more diverse samples.This study evaluates the personal values profile, leadership styles, leadership effectiveness, and their relationships with organizational differentiation among 400 Brazilian executives from 48 organizations. A closed instrument was developed to assess personal values, while existing instruments were used to evaluate leadership styles and effectiveness. Linear regression was used to analyze the relationships between personal values balance and leadership effectiveness, as well as between personal values balance and organizational differentiation. The Organizational Differentiation Model (ODM) was applied to compute the organizational differentiation index (ODI) for each organization. The study found that executives have an unbalanced personal values profile, with a predominance of economic and theoretical values. Leadership styles were found to be inflexible, with selling and sharing ideas as dominant styles. Leadership effectiveness was at a moderate level. The study revealed a high positive relationship between personal values balance and leadership effectiveness, as well as between both variables and organizational differentiation. Values are crucial in leadership, influencing perceptions of appropriate ends and means. The study highlights the importance of values in shaping behavior and leadership effectiveness. The research also emphasizes the need for leaders to be responsible, people-centered, and coherent in their actions. The study recommends a critical analysis of personal values in leadership development to ensure a comprehensive understanding of values and their impact on leadership and organizational effectiveness. It also suggests the need for democratizing leadership to make it accessible to all, and for future research to explore leadership styles and effectiveness in larger and more diverse samples.