This paper presents data from the African Food Security Urban Network's 2008 baseline survey of Cape Town. This survey found that 80% of the sampled households could be classified as moderately or severely food insecure. In urban areas the main driver of food insecurity is not availability but access. Access is typically viewed as being directly related to income. Households were found to use formal food markets, but more frequently depended on informal sector markets and informal social safety nets. The more food insecure and income poor a household was, the more likely it was to be dependent on less formal means of securing food. This suggests that there is some form of market failure in the formal food system. This paper therefore advocates for a food systems approach that validates and supports the role that the informal sector plays in urban food security.