When and Why Do Achievement Gaps in Math and Reading Emerge?

Research on achievement gaps between advantaged and disadvantaged children consistently replicates one clear pattern--all (or nearly all) of these gaps are in place prior to exposure to formal schooling, perhaps as early as age three.  That pattern directs our attention toward understanding why gaps emerge during early childhood, where most of the "action" of inequality appears to be. My hope is to identify the most consequential environmental factors that explain the magnitude of these early-forming gaps.