Instability in child care arrangements can negatively affect children's development, especially in low-income families. However, few studies have examined what predicts changes over time in child care arrangements. This paper presents findings from a unique multiyear study tracking child care use in low-income families. We estimate rich quantitative models to analyze the relationships among child, household, and care provider characteristics and four different types of changes. We find turnover in child care arrangements to be common in this low-income population. Over a period of six months, half of the children changed primary provider. Child care changes were frequently related to job loss, changes in family composition, or the changing availability of caregivers. While concerns have been raised that short spells of child care subsidy receipt cause child care instability, we found that subsidy use was not associated with higher rates of change. In addition, we found that the lower a parent's assessment of the child's experience in a particular arrangement in the prior time period, the higher the likelihood of changing providers by the next survey wave. These results indicate that low-income parents recognize quality factors and change arrangements to improve the quality of care. (author abstract)