The State of California has passed legislation requiring monitoring of microplastics in drinking water.  As such, standardized methods by which to measure microplastics are needed.  This presentation provides an overview of the measurement intercalibraiton exercise, involving 40 laboratories from 6 countries, to provide consensus on microscope, FTIR, Raman, and pyrolysis-GC/MS techniques for quantifying microplastics in such matrices.