We report [Li] and d 7 Li values for a well-characterized suite of 52 geographically (165-184°W), compositionally (SiO 2 = 46-70 wt.%), and temporally (0-38 Ma) diverse lavas and intrusive samples. The d 7 Li in these rocks range from À0.7‰ to +14.2‰, with 32 of the 35 lavas and 12 of the 17 intrusive samples falling within the depleted mantle range (d 7 Li +1.6 to +5.6‰), as sampled by mid-ocean ridge basalts (MORB). The d 7 Li values of Aleutian lavas do not exhibit the spatial trends observed in other slab component tracers, nor do d 7 Li values correlate with any slab component indicators, such as radiogenic isotopes, oxygen isotopes, or trace element ratios such as Cs/La and Th/La. The d 7 Li values in Aleutian intrusions also do not exhibit temporal trends, however, an overall positive relationship exists between d 7 Li and Th/Nd. Mixing models for d 7 Li and 143 Nd/ 144 Nd values suggest that Aleutian samples within or above the MORB d 7 Li range can be explained by addition of <1-2% sediment-derived aqueous fluid and 3% sediment melt to depleted mantle; both are required to explain the range in d 7 Li that is observed. Sediment-derived fluid exerts a stronger control on Aleutian samples having higher d 7 Li values than the MORB range, while sediment melt skews the Li isotopic compositions of MORB-range samples to slightly lower values than if sediment fluid was the only slab influence. Our study demonstrates that a slab signature may be deciphered via modeling even in arcs where spatial trends in d 7 Li values and correlations with slab component indicators are lacking.