The crucial question concerning vocabulary retrieval is how speech is produced: how the right sentences, words, syllables and phonemes are chosen to express the concept of what one intends to say. As the progress of choosing the right units is a passive one and happens in the dark of our brain, scientists can’t watch it and people can’t explain how they exactly produce speech, either. Therefore another way of exploring this topic was needed and eventually found: speech errors. Whenever someone produces a word, syllable or phoneme he didn’t intend to, it enables us to cast a glance at the production of speech. The main part of this term paper will deal with the great number of types of speech errors produced in different stages of speech production, showing us what exactly happens at these stages.