This paper examines the developmental relation of the use and understanding of Modern Greek evidential lexical items with varying degrees of metarepresentational ability. Drawing on early natural language production of two 3;6–5;10-year-olds, the paper shows that children’s use of evidentials follows a three-stage metarepresentational development. Comprehension experimental tests suggest a restricted linguistic ability and a reliable reasoning ability to interpret others’ evidential state of mind. McNemar tests which were run for the evidential linguistic pairs tested (Experiment 1) and for the evidential reasoning trials administered (Experiment 2) revealed a higher likelihood for age to affect linguistic development during 4;0–5;10 years of age, than for age to affect cognitive development of evidentiality during 3;0–5;11 years of age. The discrepancy between children’s fragile understanding of lexical evidentials and more robust recognition of consistent/conflicting evidential states is attributed to their immature metarepresentational abilities.