Although Australia is experiencing a shortage of foster carers, there is currently little understanding of why people do not become carers. This study explores the reasons given for not fostering though a survey of 897 non carers. Results indicate that, at the aggregate level, people do not become carers because they do not know anything about fostering, or because they are busy with their own children, work, or commitments to family and friends. However, if we account for heterogeneity, differences in these barriers are observed for subgroups within the sample. We investigate the structure of the market of potential foster carers by segmenting the market using cultural background as the segmentation base. Results indicate that the reasons for not fostering differ depending on the subgroup being examined. Theoretically, this suggests that heterogeneity exists within the foster care market, and that examining barriers to foster care only at the aggregate level neglects the importance of individual subsegment characteristics. Practically, results are important because they suggest that generic marketing campaigns aimed at the entire community have limited effect and that customised strategies are required to attract the particular types of carers most needed.