In late 2015, the passage of the Every Student Succeeds Act strengthened federal commitment to the use of evidence in educational innovation, focusing squarely on increasing the impact of innovation on educational outcomes. Concurrently, articles published in "Educational Researcher" examined new potential to increase the success of educational innovation through researcher-practitioner collaboration, focusing squarely on continuous improvement grounded in problems of practice. This essay examines how impact and improvement play out in the leadership of network-based improvement initiatives. Integrating critical scholarship with analysis of 20 i3-funded networks, the argument is that the practical challenges of network leaders vary inversely with system-level "innovation infrastructure", which currently provides strong support for evaluating impact but weak support for continuous improvement. Thus, additional potential to increase the success of educational innovation is argued to lie in strengthening system-level innovation infrastructure to support the simultaneous pursuit of impact and improvement.