This study explored the effects of variation in seawater pCO2 on coral calcification using experiments conducted over one month between 9 April 2018 and 18 May 2018. Branches (~4-cm long) of Acropora retusa were sampled from colonies at 10-m depth on the fore reef of Mo'orea, French Polynesia (17° 28′ 53.9004" S, 149° 49′ 50.5992" W). We tested the hypothesis that depressed calcification caused by elevated pCO2 (~1000 μatm) is relaxed (i.e., calcification increases) upon return to ambient pCO2 (~400 μatm). Corals first were incubated in ambient or elevated pCO2 for 19 days, with the result that calcification integrated over this period was reduced by 31% under elevated pCO2. The same corals were then incubated at ambient pCO2 for 11 days, during which calcification was independent of the experimental pCO2 exposure history. This material is based upon work supported by the U.S. National Science Foundation under Grant No. OCE 16-37396 (and earlier awards) as well as a generous gift from the Gordon and Betty Moore Foundation. Research was completed under permits issued by the French Polynesian Government (Délégation à la Recherche) and the Haut-commissariat de la République en Polynésie Francaise (DTRT) (Protocole d'Accueil 2005-2020). This work represents a contribution of the Moorea Coral Reef (MCR) LTER Site.