In learning a language as a means of communication, children must first coin new word-forms to express meanings for words they do not yet know. Children learn at an early age that lexicon can be used creatively, and that creativity is not simply a matter of learning which word-paradigms are available in the language, but also learning adult conventions on the uses of word-forms that carry these meanings. In an analysis of innovations in children learning Czech as their first language, both the meanings of lexical innovations and the forms used to convey these innovations are considered. One focal point is the child's behavior in a situation when a new reality must be labeled. The following approaches seem to be the most common: (1) the child coins a completely novel naming unit that has no connection with those existing in adult language; (2) the child replaces the yet unknown naming unit by one already familiar; (3) the child provides the already mastered naming unit with a new meaning; (4) the child resorts to various modifications of already existing naming units. (JL)