The chapter studies the onset of derivational morphology in the speech production of two Russian boys (aged between 1;5–2;8 and 1;8–3;0). This process involves early nouns, verbs and adjectives built by different derivation methods. Suffixation is typical for nouns and adjectives, whereas new verbs are mostly built by prefixation. Derived verbs and nouns refer to the same grammatical class as the originals and adjectives are formed from nouns. Productive use of derivation was registered several months after the first derivatives occur. The differences between dyads concern the set of semantic categories of derived words and the proportion of derivatives belonging to different grammatical classes. For one boy a further development of derivation (4;2 to 5;10) was tracked.