Hello, Here is my abstract and poster pdf! An important concept is numerical equality-- numerosities are equal if they are in one-to-one correspondence (Hume, 1739). What do kids know about the relationship between one-to-one correspondence and equality, and is it related to their number word meanings acquisition? Piaget (1965) addressed this through his conservation task and found that kids could not conserve number until after mastering the count routine. Subsequent work found that their failures may be due to pragmatic (McGarrigle & Donaldson, 1975) task demands instead of lack of number knowledge. The age at which kids conserve has not been resolved or brought into alignment with modern number acquisition theories (Carey, 2004; Sarnecka & Carey, 2008; Wynn, 1990). Our study examines when kids understand one-to-one correspondence as the basis of equality. We tested 80 kids on Piaget’s conservation task and tasks measuring number knowledge. Kids’ conservation was unrelated to their number knowledge in Piaget’s conservation task. When we highlighted the importance of exact number, kids with greater number knowledge’s performance increased with age, suggesting that pragmatic task demands may obscure kids’ number knowledge.