This paper deals with the positive relation some studies have gathered between the implementation of neoliberal policies and the expansion of the penal system. It begins by pointing out some of the most significant changes in penality in Spain, and it suggests that the attention Spanish sociology has paid to them is scarce. After defending the pertinence of studying punishment as a social institution, it points to the international empirical evidence that shows strong correlations between these two variables, much more predictable than those existing between the penal system and crime rates. After pointing out the limitations of these studies, thinking about neoliberalism as a policy paradigm which should find itself reflected in the institutional configuration is proposed, and other forms of more qualitative research (or, preferably, case studies) are called for, in order to throw some light on some of the various existing problems in transforming these correlations into causal relations.