In this paper I discuss the influence the Spanish language has had on American English, as well as the influence that American English has had on Spanish at the same time. Because of the long-lasting and strong mutual contacts between two languages, Spanglish developed as their mixture. The analysis of Spanglish would be impossible without a short presentation of historical circumstances in which it developed, so it is included in the first part of the paper. In the body of the paper I analyse some important terms connected with the development of Spanglish and other similar linguistic phenomena, as well as some striking phonological, morphological, syntactical and semantic features of it. I also give a short review of the presence of Spanglish in nowadays media, that is, in the press and music. At the end of the paper the passage from a text written in Spanglish is attached as an illustration.