Large-scale Greenland ice sheet projections of sea level, such as those run during the ice2sea and SeaRISE initiatives, have shown that the initial state of the Greenland ice sheet used in the model has a large effect on the projected sea level rise, leading to large uncertainties. The initMIP-Greenland intercomparison exercises allow ice sheet modelers to compare, evaluate and improve their initialization techniques and estimate their associated uncertainties. Two experiments were performed by each modeling group: (1) produce an initial present-day state of the Greenland ice sheet and (2) simulate the response of this initial state in two idealized forward experiments. The forward experiments allow modelers to evaluate the model drift and response to a large perturbation. Though this effort, the initialization methods, and datasets have been identified that will be needed for the 100-200 year projections planned for CMIP6. A freely available benchmark dataset has also been generated to help modelers evaluate and improve future initialization methods.