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North Atlantic right whalesEubalaena glacialishave been observed feeding in Cape Cod Bay (CCB) for over 8 decades, making CCB the most consistent known feeding habitat under shifting ocean and climate conditions. Determining the composition of the right whales’ prey resource in a stable feeding habitat during a period of environmental change will inform conservation efforts throughout their habitat range. We compared zooplankton sampled in the paths of skim-feeding right whales to the bay-wide zooplankton resource in CCB over 23 yr. The dominant zooplankton taxa in CCB werePseudocalanuscomplex,Calanus finmarchicus, andCentropagesspp. during the winter/spring seasons. The succession of these 3 dominant taxa—Centropagesspp. toPseudocalanuscomplex (day of the year [DOY] mean ± SD: 34 ± 3) toC. finmarchicus(DOY 92 ± 3)—has provided right whales with a stable, multi-month food resource in a small portion of their greater North Atlantic habitat. We found that right whales targeted aggregations of non-dominant prey groups:Pseudocalanuscomplex andCentropagesspp. aggregations whenCentropagesspp. dominated the bay-wide zooplankton community;Pseudocalanuscomplex patches andC. finmarchicuspatches whenPseudocalanusdominated; and primarilyC. finmarchicuscopepodite stage CIV and CV aggregations when CIII dominated bay-wide abundances. Over the time series, we found thatCentropagesspp. abundance increased andC. finmarchicusdecreased only at the beginning of the season. CCB remains a critical foraging habitat for right whales due to the phenological cycle of their prey and limited inter-annual changes in prey abundance.