Research impact is a complex phenomenon that denotes how research results and the people and organizations that produce them contribute to changes elsewhere. These changes come in the form of innovation and economic growth but also in areas such as health and care, agriculture, national security, environmental issues, and policymaking. Traditional studies of impact have studied the consequences of research and the antecedents of its effects, often with an aim to quantify the contributions of research and development (R&D) in different sectors of society. Many central relationships between specific outcomes (such as innovation incidents) and specific inputs (such as funding and public support for firms or research performing organizations) have been highlighted. But the processes and mechanisms that link inputs and outcomes in complex and sometimes surprising ways are therefore intricate to disentangle conceptually and empirically.