ABSTRACT This paper highlights work from a Master's study which aimed to identify developmental patterns of transitional talk in normal children and code them. Particular attention was paid to Scollon's (1979) coding of vertical talk sequences and the concept of a developmental continuum. Longitudinal conversational samples were collected from two boys between the ages of 19–21 months, recorded in interaction with their mothers. Transcripts were coded for vertical features such as lexical overlap and speaker turn. Graphical display of code frequencies revealed similar trends for the two subjects. Utterance sequences involving lexical repetition were characteristic of the early‐to‐mid transition phase and showed no effect of speaker turn, whilst those involving lexical difference typified the mid‐to‐late transition phase and were sensitive to speaker turn. The transition from single‐ to multi‐word utterances only gradually became independent from lexical overlap in the child's own prior talk and continued to be dependent on the mother's intervening talk. Discussion focuses on the concept of a three‐dimensional approach to the presyntax transition analysing horizontal, vertical and diagonal utterance sequences. The clinical relevance of the work is explained.