Richard Skolnik, lecturer at Yale's School of Public Health, addresses why health outcomes depend on more than health systems alone. This lesson from his Essentials of Global Health course argues that lasting gains in areas like nutrition, sanitation, and disease control require coordinated action across sectors such as education, agriculture, water and infrastructure, and urban planning, not health ministries working in isolation. Skolnik walks through examples of intersectoral collaboration, discussing what makes such partnerships succeed or fail, including governance structures, financing, and the political will needed to align competing agencies around a shared goal. He frames this within the broader arc of the course, which surveys the major global health challenges expected over coming decades and the science, technology, and collective action needed to meet them. The lecture is plainly delivered, slide-supported, and aimed at students building a working knowledge of how public health policy actually gets implemented across government sectors.