How to increase diversity in computer science is an important open question in CS education. A number of best practices have been suggested based on case studies; however, for scaling these efforts up in a sustainable fashion, it remains unclear which types of initiatives are most effective in which contexts. We examine gender diversity initiatives in CS education from a policy analysis perspective, adapting McDonnell and Elmore's 1987 notion of policy instruments, wherein the initiative is the unit of analysis. We present a conceptual framework for categorizing the different policy instruments by a cross of 'leverage' and 'targetedness', and discuss how different types of initiatives will scale. We argue that universally-targeted, high-leverage initiatives are most important for scaling up diversity initiatives in CS education, with medium-leverage being a stepping stone to high leverage change.