This thesis investigates the word formation processes of the neologisms in the Harry Potter books by JK Rowling. The aim is to find the frequencies of these processes and then discuss why the frequency looks this way. By collecting and analysing the neologisms with the help of the classification of Plag (2003) and Ljung (2003), the frequencies of the different formation processes is established. The reasons why the distribution of word formation processes looks this way is then discussed and compared to the background information about the author. The conclusion is that compound is the most frequent word formation of this sample. The arguments why the distribution looks this way could be that the semantic meaning of the Harry Potter words is important and that many of the neologisms are based on humour, mythology and folklore.