Pennebaker’s research explores the links between traumatic experiences, expressive writing, natural language use, and physical and mental health. Across numerous real-world contexts, his studies have demonstrated that the words people use serve as powerful reflections of their personality and social worlds. For example, his analyses of over 1,000 people who wrote blogs in the weeks before and after September 11 terrorist attacks showed that the journal entries revealed pronounced psychological changes in response to the attacks. His talk will address the fact that most language-based computer programs analyze content-heavy words (such as nouns and regular verbs) and throw out “junk” words (such as pronouns, prepositions, and articles) to understand people’s thinking, buying, searching, and other behaviors. According to Pennebaker’s work, analyses of junk words can yield important insights into the social and psychological processes of people across cultures and languages. He will talk about his recent studies, which point to the role of junk words in identifying personality, depression, status, honesty, group cohesiveness, and other individual and group behaviors.