This dissertation study used a merged set of longitudinal data from Wisconsin administrative records and the state's Unemployment Insurance database. Data included detailed information on the monthly receipt of child care subsidies and eligibility status, employment patterns and earnings, and demographic information about children and families who received child care subsidies during a longitudinal observation period. The study examined three questions on the patterns of child care subsidy use, factors associated with the stable use of subsidies, and the relationship between child care subsidy use and changes in earnings using two cohorts of mothers: mothers who received TANF benefits between September 1997 and August 1998 (1997 TANF recipient sample, n = 16,624) and mothers who applied for child care subsidies between March 2000 and February 2001 (2000 low-income mothers sample, n = 12,594). (author abstract)