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Textures and compositional relationships associated with dark-colored, fine-grained enclaves in the Cadillac Mountain and Somesville granites, Mount Desert Island, Maine, preserve abundant evidence for contamination of host granitic magmas by enclave liquids. Fine-grained enclaves, which apparently represent chilled magmatic droplets, have affected the composition and texture of the host granites by three possible mechanisms: (1) crystallization of feldspar-quartz-hornblende pegmatite pods from fluids of enclave origin in the granite surrounding enclaves, and the disaggregation of the pods and dispersion of crystals into the granite; (2) ionic exchange between enclaves and granitic magmas; (3) the generation around enclaves of rinds consisting of an inner alkali feldspar-quartz zone and an outer zone of hornblende-enriched granite. Coarse-grained pegmatite pods that occur outside of enclaves may result from migration of a hydrous residual fluid, evolved during enclave crystallization, out of the enclave, and into the partially crystalline magma. Crystallization of minerals from this liquid, and their disaggregation into the host granite, contaminate the granite with minerals comprised of exotic components that originated in the enclaves. High zircon concentrations around enclave boundaries may result from transport of zirconium ions in the hydrous residual fluid out of the enclave magma into the granitic magma. The occurrence of alkali and plagioclase feldspars near enclave margins and in pegmatite pods may record hydrous fluid-induced lowering of the solidus to intersect the solvus in the feldspar system. Ionic diffusion, at temperatures either above or below the enclave magma solidus, may be responsible for clinopyroxene-albite and clinopyroxene-potassium feldspar enclave compositions, with sodium and/or potassium diffusing at relatively high rates across enclave boundaries (Baker 1990). Thermal calculations suggest that the alkali feldspar-quartz zones of the rinds surrounding enclaves may result from resorption of alkali feldspar and quartz crystals in the granitic magma by heat of cooling and crystallization of enclave material. The interaction between the hot enclave and the alkali feldspar-quartz composition liquid may be analogous to that between a pluton and meteoric water in a hydrothermal system. The segregation of alkali feldspar-quartz and hornblende-rich zones may result from the minimum melt composition fluid migrating toward the enclave, leaving behind unmelted hornblende, as part of a convection circuit set up by the enclave. Alternatively, hornblende-rich zones concentric to and outside of the alkali feldspar-quartz rinds may record the limit of movement of a front of hydrous fluid driven from the enclave boundary down a thermal gradient.