Replication Protein A (RPA) is a heterotrimeric single stranded binding protein required for eukaryotic DNA replication, repair and recombination. The primary biochemical function of RPA is to protect and preserve single stranded DNA from nucleolytic degradation and hairpin formation. Downstream cellular responses to detect DNA damage include regulation of cell‐cycle checkpoints, induction of DNA repair and programmed cell death. These responses are mediated through two closely related protein kinases ATM (Ataxia Telangiectasia mutated) and ATR (Ataxia Telangiectasia‐mutated and Rad3‐Related). ATM is activated by double strand breaks while ATR is activated by a variety of lesions resulting in stalled replication forks. Genetic analysis of RPA1, by employing T‐DNA insertion mutants of the five Arabidopsis RPA1 subunit genes, revealed divergence of the RPA1 gene family into three functionally distinct groups. RPA1B and RPA1D are required for normal DNA replication, RPA1A and RPA1C play a role in meiosis, and RPA1C and RPA1E are primarily involved in DNA repair. Our analysis shows that within the repair group individual RPA1 subunits display unique functions in response to DNA damage. Analysis of hypersensitivity responses to replication blocking agents and DNA damaging agents suggests that RPA subunits RPA1C and RPA1E play leading roles in DNA damage repair. Genetic interactions of RPA1C, RPA1E and ATR revealed that a combination of rpa1c, rpa1e and atr mutants create additive hypersensitivity phenotypes consistent with each functioning in unique repair pathways.