In two experiments subjects were interrupted while listening to a two-clause sentence just before the last word of either the initial clause or the final clause. In Experiment I subjects were timed on their decision about whether a verb-object phrase was consistent in meaning with the sentence fragment they had just heard. Overall these decisions were made more quickly when a main clause was interrupted than when a subordinate clause was interrupted, but the size and direction of main-subordinate differences varied with the causal-temporal properties of subordinate clauses. In Experiment II subjects were timed on their decisions about whether a particular probe word had occurred in the sentence fragment. Target position effects differed for main and subordinate clauses, but again, these effects were related to causal-temporal relations between clauses. The two experiments together suggest that interclause semantic relations affect the immediate processing of clauses.