This article concentrates on the continual sequence of sound acquisition process in individual subjects. The basic material is taken from three longitudinal studies regarding three Latvian-learning (monolingual) children; additional observations were made of five other children. In spite of the fact that Latvian is rich in consonantal clusters, all children had difficulties in mastering them correctly: they tried to avoid them by omission of one or two consonants or by replacing them with other sounds. Even hypercorrect substitutions appeared. Medial clusters occurred much earlier than clusters in other positions, and final clusters several months before initial clusters. Similar observations in Czech children learning their mother-tongue point to some universal character of this phenomenon since consonantal clusters are absent in many world languages or are used in special positions, and they are among the first features which disappear in aphasia.