The present invention relates to compounds of Formula I, IA, II, IIA, III, or IIIA and their pharmaceutical uses. Particular aspects of the invention relate to the use of those compounds for the selective inhibition of one or more caspases. Also described are methods where the compounds of Formula I, IA, II, IIA, III, or IIIA are used in the prevention and/or treatment of various diseases and conditions in subjects, including caspase-mediated diseases such as sepsis, myocardial infarction, ischemic stroke, spinal cord injury (SCI), traumatic brain injury (TBI) and neurodegenerative disease (e.g. multiple sclerosis (MS) and Alzheimer's, Parkinson's, and Huntington's diseases).