The purpose of this report, as prepared by American Institutes for Research (AIR), is to help Sonoma County develop a plan "to make universal preschool a reality" as recommended in A Portrait of Sonoma County (Burd-Sharps & Lewis, 2014). In line with Strategies to Reduce Poverty in Sonoma County (Blue Sky Consulting Group, 2014), this report also offers guidance on how to phase in access to quality preschool, beginning in the areas of highest unmet need. This document is intended to replace an earlier version of the report submitted in October 2015; this April 2016 version provides different and more refined phase-in scenarios based on new information and assumptions. Specifically, this report will do the following: Describe the key features, including funding levels, phase-in plans, and finance mechanisms, of 12 city and other regional preschool initiatives being implemented across the United States. Analyze potential funding options. Provide two estimates for the per-child cost of providing full-day (i.e., eight hours), full-year (12 months) preschool in Sonoma County: one based on the current expenditures for programs meeting the minimum standards for Title 5 State Preschool or Head Start in California, and one with an increase in compensation to a living wage intended to help recruit and retain qualified staff. Present eight options for phasing in universal access to quality preschool in the county across a five- to 10-year period, beginning in the areas of highest need and the least access to preschool. Make recommendations for funding and phasing in access to quality preschool for all children in Sonoma County. (author abstract)