This document summarizes work being done to improve human reference genomes using alternative samples. It notes that the initial human reference is incomplete and additional sequences are needed to represent diversity. It then describes efforts to generate "platinum" quality assemblies of additional samples, including CHM1 and CHM13, using long read sequencing and scaffolding with optical mapping. Initial assembly stats are provided for CHM13 and NA19240, and future plans include integrating targeted sequences, adding more diversity, and developing tools to utilize alternate haplotypes in the reference.