This document discusses New Zealand's open government data initiative and what it means for data suppliers, users, and society. It defines open data as being accessible, machine-readable, and re-usable. Open data can enable economic growth through new businesses and tools, better social outcomes from improved daily decisions and analysis, and government efficiencies from single authoritative sources and evidence-based policy. Realizing these impacts will take bold changes and many years of engaged government agencies regularly supplying high-value data and engaged users developing applications, while addressing challenges around funding, capabilities, and assessing long-term impact.