An eye-movement monitoring experiment investigated readers' response to temporarily ambiguous sentences. The sentences were ambiguous because a relative clause could attach to one of two preceding nouns. Semantic information disambiguated the sentences. Working memory considerations predict an overall preference for the second of the two nouns, as does the late closure principle (Frazier, On comprehending sentences: Syntactic parsing strategies. Ph.D. dissertation, University of Connecticut. West Bend, IN: Indiana University Linguistics Club, 1979). Previous studies assessing preferences for such items have obtained mixed results. On-line assessments show that working memory affects the degree of preference for the first noun, with lower capacity readers having a greater preference for the second noun (Felser et al., Language Acquisition: A Journal of Developmental Linguistics, 11, 127-163, 2003; Traxler, Memory & Cognition, 35, 1107-1121, 2007). Off-line assessments indicate the opposite pattern of preferences when the test sentences are displayed on a single line (Swets et al., Journal of Experimental Psychology: General, 136, 64-81, 2007). However, when implicit prosody is manipulated by displaying the sentences with a break between the second noun and the relative clause, the off-line assessments indicate that readers prefer to attach the relative clause to the first noun. In this experiment, readers' undertook a working memory assessment and then read test sentences that were displayed across two lines, with a break appearing after the second noun and before the relative clause. The eye-tracking data indicated an overall preference to attach the relative clause to the first noun, and there was little indication that working memory moderated the degree of preference for this configuration. Hence, it appears that readers' implicit prosodic contours rapidly affect resolution of adjunct attachment ambiguities.