The poly(ADP-ribose) polymerase (PARP) family catalyzes the post-translational modification known as ADP-ribosylation (ADPr) from donor molecule nicotinamide adenine dinucleotide (NAD+). The PARP family consists of 17 members (in humans) based upon a conserved catalytic domain. The family is further divided based on whether they catalyze mono-ADPr, the transfer of a single ADP-ribose to protein targets, or poly-ADPr, the transfer of additional ADP-ribose units onto the initial ADP-ribose modification. The poly-ADPr PARPs have been extensively studied, most notably PARP1 and PARP2, for their involvement in DNA damage recognition and repair. The mono-ADPr PARPs have only recently been investigated in various roles throughout the cell. Their study has been limited mostly to knockdown techniques to identify cellular phenotypes. These genetic approaches remove the PARP from the cellular system and do not provide the ability to identify specific targets of PARPs, nor do they allow a dynamic study of PARP biology. They also preclude the ability to connect PARP catalytic activity to a given process without ruling out other domain features within PARPs.