The purpose of this paper is to examine the responsiveness of partnered women's labour supply to the price of child care in Australia. We show that the way in which child care prices are constructed can have very large impacts on findings, which is an important methodological point for researchers studying the effects of child care prices in any context. We find, in contrast with previous studies of Australia, that partnered women decrease their labour supply in response to an increase in the price of child care. We show that measurement error in the construction of the child care price is the main factor which explains the difference between our findings and previous Australian studies. (author abstract)