This paper proposes, empirically motivates and describes a pseudo-deterministic model of Human Language Processing (HLP) implemented in the ACT-R cognitive architecture (Anderson, 2007). The model reflects the integration of a highly parallel, probabilistic activation and selection mechanism and non-monotonic context accommodation mechanism (with limited parallelism) with what is otherwise a serial, deterministic processor. The overall effect is an HLP which presents the appearance and efficiency of deterministic processing, despite the rampant ambiguity which makes truly deterministic processing impossible.