Effective leadership has been advocated as important in guiding successful conservation programmes to achieve more impactful biodiversity results. Conservation work demands diverse capabilities, so organisations must be aware of what influences leadership effectiveness, including the influence of gender. The Conservation Excellence Model (CEM) allows assessment of conservation project effectiveness, including leadership aspects. The objectives of this study are to: 1) evaluate a mammal species conservation programme in Brazil, a region of critical importance to biodiversity, 2) benchmark with other conservation programmes to identify effective practices, and 3) conduct an in-depth evaluation of leadership skills to explore gender-related aspects of leadership. This study emphasises that good conservation organisational practices are related to Monitoring and Evaluation (within Strategic planning and Theories of Change) and the engagement of the local community. Both male and female leaders displayed common leadership characteristics such as the ability to build partnerships, establish the programme's purpose and vision, and delegate tasks. Both females and males were considered committed leaders, although only men were described as "role models". Other differences included how women were characterised as "hands-on managers" and men as "giving training opportunities". Leadership roles appear male-dominated, representing challenges for women to achieve higher positions. Women notably face a lack of mentorship, lengthy work hours, exclusion from decision-making, and sexual harassment. Nevertheless,