The gut microbiome is a vast, variable, and largely unexplored component of human biology that sits at the intersection of heritable and environmental factors, and represents a rich source of novel chemistry that is already known to be compatible with the human body. This alone would make it a promising place to search for new therapeutics, but recent work has also identified gut microbiome abnormalities in patients with a number of psychiatric disorders, including anxiety disorders-suggesting that not only treatments, but cures may lie therein. Here, we'll discuss two known "para-endogenous" anxiolytics-γ-hydroxybutyrate and the neurosteroid allopregnanolone-which have recently been discovered to be produced by the microbiome.