Poly-ADP-ribose-polymerases (PARPs) are a family of 17 post translationally modifying enzymes in humans that catalyze the transfer of ADP-ribose from nicotinamide adenine dinucleotide (NAD+) onto target amino acids and nucleotides. PARPs can append long dendritic chains of ADP-ribose (poly-ADP-ribosylation, or PARylation) or monomers of ADP-ribose targets (mono-ADP ribosylation, or MARylation) to their). While the majority of the PARPs catalyze MARylation, there has been surprisingly little attention given to these enzymes or modification the last ten years. Even now, as evidence of the MARylating PARPs importance in basic biology and human diseases masses, very little is known about the function, targets, or biological mechanisms of these PARPs. Conversely, the PARylating PARPs are well understood.