Advisory ratings and content descriptions are assigned to motion pictures by the Motion Picture Association of America (MPAA), and represent the primary social policy in the United States for advising parents about movie content, with a goal of limiting minor children's exposure to material deemed inappropriate for their age. To examine possible historical trends in MPAA ratings information, the present study analyzed the content of PG, PG-13, and R movie rating justification phrases (e.g., "Rated PG-13 for violence and language") applied to movies released in the years 1993-2005. A random sample of 1820 movie titles was selected, and all words in the rating justification phrases were coded as primary content terms or modifier terms. Results indicated that content terms for language, violence, and sexuality appeared frequently at all rating levels. Historical trends were found for terms indicating stronger depictions of violence and language and more mature thematic material in PG movie phrases, and more adult language, substance use, and sexual content in PG-13 movie phrases, across the sampled years, a pattern termed "ratings creep." Policy changes and psychological processes affecting MPAA raters and the ratings process are discussed as plausible causes of ratings creep, as are implications of these ratings changes for media consumers and society at large.