The Biogeochemical-Argo program aims to develop a global network of 1000 Argo profiling floats with oxygen, nitrate, pH, and bio-optical sensors. The BGC-Argo array will operate as one component of the One Argo array, including Core-Argo and Deep-Argo. Contributions of floats with biogeochemical sensors have come from over 20 nations. The BGC-Argo array will address key questions such as: What is the ocean's role in regulating the carbon cycle? What are the drivers of open ocean deoxygenation? How do physical changes in mixing and circulation affect nutrient availability and productivity? Is the timing and location of phytoplankton blooms changing?