Carotenoid cleavage dioxygenases (CCDs) are mononuclear non-heme iron enzymes that classically split carotenoids at specific alkene bonds producing apocarotenoid products. Certain members of this enzyme superfamily have evolved to process alternative substrates with varying regio- and stereo-selectivity, and some catalyze alternative reactions including alkene geometric isomerization and ester hydrolysis. Products of these reactions are vital for a broad array of biological processes ranging from embryonic development and visual function in animals to drought resistance and pathogen susceptibility in plants. The importance of CCDs in biology coupled with the interesting variability in their catalytic activity has motivated efforts to understand the molecular inner workings of these enzymes. In this talk, I will discuss recent experimental findings from our laboratory that have shed light on the structural basis for some of the diverse catalytic functions found among CCDs.