Indonesian language has many loan words used both in written and spoken communication, in formal and informal situation. This phenomenon becomes the writer?s interest in doing a study on the use of loan words that come from English found in Indonesian Cosmopolitan magazine. This is a qualitative study, in which the writer analyzes the word formations, phonological and spelling changes of loan words. She collects the data from the articles ?Cover Stories? section only from Indonesian Cosmopolitan magazine issued in October 2004 and April 2005. The writer applies theory of word formation and assimilation proposed by Godby, et al (1982), theory of meaning as reference and meaning as context and use proposed by Frawley (1992). The writer also u...