This document summarizes Ezio Manzini's lecture on design in the age of networks and sustainability. The lecture discusses how social and environmental crises create opportunities for new sustainable economies based on green, social, and networked models. It provides examples of social innovation in areas like food, public services, and digital platforms. Manzini argues that designers can help drive sustainable change by taking a systemic approach to design for social innovation. He outlines four activities for designers: using co-design tools to facilitate participation; designing solutions to scale local initiatives; coordinating projects to direct local innovations; and building networks to promote social innovation.