In most languages, sentences can be broken down into words, which themselves can be further decomposed into units that contain meaning of their own, so-called morphemes (e.g., “play” or plural form “-s”). Morphemes are the main building blocks and tools, which we use to create and change words. The representation of morphologically complex words (inflected, derived, and compound) in the mental lexicon and their neurocognitive processing has been a vigorously investigated topic in psycholinguistics and the cognitive neuroscience of language. Are morphologically complex words such as “player” and “plays” decomposed into their constituents (i.e., into their stem “play” and plural suffix “-s” or agentive suffix “-er”) or are they processed and represented holistically (“player” and “plays”)? Despite extensive research, many important questions remain unanswered. Our Research Topic addresses several currently unresolved topics on the time-course of morphological analysis and the relationship between form and meaning information in morphological parsing. The studies also seek answers to the questions of how inflections and derivations differ in the way they are handled by the mental lexicon, how compound words are recognized and produced, as well as how morphologically complex words are processed within the bilingual mental lexicon, as well as by different clinical populations.