Findings on perception of missing subjects in complement clauses are reported in two experiments with school-aged children and adults. The complement clauses were embedded into four matrix verbs in Greek, such as Ask (ask information), Promise, Tell1 (orderl command), and Tell2 (give information) equivalent to English in syntactic and semantic constraints. The data from Experiment 1 show the following: (1) Perception of missing subjects in Ask, Promise, and Tell1 complement clauses is significantly higher than in Tell2, but Guttman coefficient of scalability (.58) was slightly lower than the required one (over .60) to document a developmental sequence between the four constructions. (2) In general, these results, as other findings, contradict with Minimal Distance Principle (MDP) advocated by Chomsky (1969, 1972). (3) Differences in perceiving the source (i.e., NP1) in Ask and Promise and the goal/recipient (i.e., NP2) as subject in the complement clauses on Tell1 and Tell2 cannot consistently be explained by the Semantic Role Principle (SRP) postulated by Maratsos (Lederberg & Maratsos, 1981; Maratsos, 1974) either. (4) Results from Experiment 2 with three age groups, despite minor differences, confirm the results in Experiment 1, suggesting that comprehension of complement clauses with Ask, Promise, and Tell1 is a prerequisite to comprehension of complement clauses with Tell2, according to Guttman coefficients of scalability (over .60 for all groups). (5) The findings are discussed within the framework of the SRP, but the emphasis is placed on the interaction of semantic and pragmatic presuppositions over processing the four construction types.