Two experiments tested the hypothesis that processing load during sentence comprehension decreases more at the termination of functionally complete linguistic sequences than it does at the termination of functionally incomplete sequences. Functionally complete sequences were defined as consisting of complete, coherent, and fully explicit propositional structures: subject-verb-(object). It was shown that identifying sentence comprehension units with functionally complete sequences accounts for systematic fluctuations in processing load in cases for which purely syntactic definitions of sentence comprehension units make no predictions. Further empirical elaborations in the definition of functional completeness were discussed. © 1979, Sage Publications. All rights reserved.