Real-time language comprehension is an important area of focus for a candidate unified theory of cognition. In his 1987 William James lectures, Allen Newell sketched the beginnings of a comprehension theory embedded in the Soar architecture. This theory, NL-Soar, has developed over the past few years into a detailed computational model that provides an account of a range of sentence-level phenomena: immediacy of interpretation, garden path effects, unproblematic ambiguities, parsing breakdown on difficult embeddings, acceptable embedding structures, and both modular and interactive ambiguity resolution effects. The theory goes beyond explaining just a few examples, it addresses over 80 different kinds of constructions. Soar is not merely an implementation language for the model, but plays a central theoretical role. The predictive power of NLSoar derives largely from architectural mechanisms and principles that shape the comprehension capability so that it meets the real time constraint.