The role of context constraints on the time course of predictive inferences during reading was investigated. Constraints (low vs. medium vs. high) were determined by manipulations of a context sentence that affected the extent to which an event was predictable. The time course was assessed by variations in the delay (50 vs. 550 vs. 1050 ms) between the context to be read and a target word to be named. This word represented either the predicted event (inferential target) or an unlikely event (non-predictable target). With a 1050-ms delay, there was facilitation in naming the inferential target word following the predicting context, relative to a control context, regardless of the degree of constraints. With a 550-ms delay, facilitation did not occur unless there were high constraints, even if the context presentation rate was slowed down. With a 50-ms delay, facilitation was not observed even under high constraints. It is concluded that enhanced context constraints speed the time course of predictive inferencing to some extent: under enhanced constraints, predictive inferences are made earlier, but do not become automatic.