Background: Early care and education (ECE) has lasting, positive effects on children's school readiness (Phillips et al., 2018; Yoshikawa et al., 2013). Over the past several decades, access to city or state-funded prekindergarten (pre-K) has increased considerably (Friedman-Krauss et al., 2023) with well-documented, positive impacts on child outcomes (Cascio & Schanzenbach, 2013; Gormley et al., 2018; Weiland & Yoshikawa, 2013). An open question is how the expansion of pre-K programs has affected their local ECE markets. Evidence from New York City suggests that the expansion of locally-funded pre-K programs can crowd out existing programs, particularly those that care for younger children (Brown, 2018). Yet evidence on whether the expansion of locally-funded pre-K crowds out existing care in other contexts--and in particular the expansion of universal rather than targeted pre-K--remains limited. In 2019, Chicago began offering universal pre-K through Chicago Public Schools (CPS), with the goal of expanding access to free, full-day pre-K to all eligible 4-year-old children in the city. To reach universal access, Chicago's UPK model utilizes a mixed delivery comprised largely of school-based pre-K programs in CPS elementary schools, combined with some Illinois Child Care and Development Fund (CCDF) and Head Start programs. However, a major question among community members in Chicago, even prior to COVID-19, was whether the school-based pre-K expansion of free, full-day programming would have a negative impact on the broader birth-to-five ECE market. Purpose: In the current study, we explore the extent to which the Chicago ECE market was affected by the compounded effects of the UPK expansion and COVID-19. We examine how Chicago's UPK expansion in 2018-19 through 2021-22 affected community-based organizations (CBOs), including center-based and family child care programs, in the birth-to-five ECE market in Chicago. To understand whether the UPK expansion led to program closures or reduced capacity, we address the following: 1. What was the impact of the UPK expansion on the CBO closures? 2. What was the impact of the UPK expansion on the capacity of CBOs that remained open throughout the expansion period in the local ECE market? Data and Sample: We combine administrative data from the Chicago Public Schools (CPS) and the Illinois Network of Child Care Resource and Referral Agencies with American Community Survey data from 2017 to 2023 to create a comprehensive dataset of all CCEE programs in Chicago. Our key outcomes include the number of CBOs in local ECE markets and the average capacity of CBOs that remained open across throughout the expansion period. Thus, we examine whether the UPK expansion led to closures of community-based programs, and whether it affected the capacity of programs that remained open. Analytic Approach: To understand the impact of Chicago's UPK expansion on local ECE markets, we divide the city into 164 hexagons, an approach proposed by Brown (2018). This allows us to approximate local ECE markets that avoids market overlap and creates uniformly sized units of observation (see Figure 1). Each hexagon reflects the range of ECE options households within it may consider when making childcare decisions. We then estimate an event study model that utilizes variation in the timing and location of the UPK expansion across local ECE markets in Chicago. Our approach compares changes in the number and capacity of CBOs in markets where Chicago UPK expansion occurred relative to markets with no pre-K expansion, and employs the two-step detrending procedure proposed by Goodman-Bacon (2021). This approach accounts for all time-invariant market characteristics, as well as any contemporaneous policy changes that affected programs across Chicago over this time period, to provide a causal estimate of the UPK expansion. We examine changes in the number and capacity of CBOs separately for center-based and family child care programs. Findings: We find that the UPK expansion led to a slight decrease in the total number of CBOs (around half a program on average; see Table 1), concentrated among family child care programs with no effect on center-based programs. There was no impact on the average capacity of CBOs (Table 2). The slight decline in the number of CBOs was more than offset by an increase in full-day school-based pre-K seats. Overall, the UPK expansion led to a substantial increase in the number of free, full-day seats in school-based programs with minimal impact on community-based programming. Implications: We find that the UPK expansion results in a small decrease in the number of CBOs, mainly among family child care programs. But since family child care programs on average serve small numbers of children, and because many new seats were added through school-based pre-K, we observe an "overall" increase in capacity within the child care market. Thus, our findings show that it is possible to expand pre-K access for 4-year-old children without disrupting the broader ECE market that services children birth-to-three.