Editors' Summary: Cooper Industries v. Aviall Services, a 2004 U.S. Supreme Court case, challenged the legal community's understanding of rights of cost recovery under CERCLA, ruling that PRPs who voluntarily cleaned up property did not have a cause of action in contribution under §113(f). However, earlier this year, in United States v. Atlantic Research Corp., the Court held that PRPs who voluntarily clean up contaminated properties may have a right of recovery under §§107(a)(4)(B) or 113(f). In this Article, Jeffrey M. Gaba explores the issues left unresolved or convoluted by these two opinions. He begins with background on the private rights of cost recovery under CERCLA, and then parses these two decisions. He concludes by encouraging the Court to reconcile the different parts of CERCLA to create a coherent set of rights to cost recovery for PRPs.