The influence of linguistic and social factors on (r) in Boston and two New Hampshire towns is described. The preceding vowel and geographic, ethnic, and age-related differences were found to have strong effects. In comparison to Bostonians, New Hampshire speakers exhibit a higher rate of rhoticity, and fewer factors constrain their variability. Younger speakers are more rhotic than older speakers, as are more educated speakers and those in higher linguistic marketplace positions. This study demonstrates that these patterns fit the transmission (within Boston) and diffusion (to New Hampshire) framework (Labov, 2007) only with the addition of accommodation theory (Niedzielski & Giles, 1996), which connects our linguistic findings to evidence that many New Hampshire residents do not identify with Boston. The effects on (r) in other studies are compared to determine which effects are particular to individual communities (nonuniversal) and which occur across all communities examined. The nonuniversal effects are therefore available as measures of contact-induced change. This study introduces a method for quantitatively comparing the amount of change between communities.