This study explored the relationship between financial literacy and the use of interest-only mortgages using data from the 2009 National Financial Capability Study (NFCS). A series of analyses were conducted to investigate characteristics associated with the use of an interest-only mortgage as a primary mortgage, as compared to fixed-rate mortgage and adjustable-rate mortgage (ARM) options. Consistent results indicate the individuals who incorrectly answered questions related to compound interest, mortgages, and diversification were more likely to be using an interest-only mortgage. Respondents with higher reported math skills were less likely to use an interest-only mortgage, whereas individuals with higher levels of financial confidence were more likely to be using one. These results reinforce concerns about a household's ability to understand and evaluate complex mortgage products.