According to Matsumoto (1993), the Japanese associate smiling with negative emotions while smiling indicates happiness to Americans. Yamada (1998) explains that smiles and laughter demonstrate the need to get along with others and to signal uneasiness in Japanese conversations, whereas Americans laugh to bond and show camaraderie. She also argues that American laughter is triggered by humor while Japanese smiles are not necessarily triggered by jokes. This study compares the use of smiles and laughter in English and Japanese conversations to investigate how frequently they are used in conversations and in what context. In particular, this study will explore the function of facial expression by examining how smiles and laughter are used in interaction. The data used for this study is 20 minutes of Japanese conversations and 20 minutes of English conversations from five four minute conversations of pairs of female friends for both language data sets. The data a! re first quantitatively analyzed. Occurrences of smiles and laughter in each data set are categorized into five types: beam, grin, chuckle, giggle and roar, and the occurrences of each type are counted. Then, the data are qualitatively analyzed by examining how smiles and laughter are triggered in context. The data analysis shows Japanese conversations to have more smiles and laughter than American conversations (115 in Japanese conversations versus 86 in American conversations). Japanese participants use more grins and chuckles than American counterparts. In addition, laughter is triggered frequently by quotes and proper nouns in English conversations, while smiling often occurs with quotes and negative comments in Japanese conversation. Furthermore, smiling and laughter are used to upgrade positive comments or downgrade negative comments in both language data sets. This study concludes that facial expressions, such as smiles and laughter, can be employed in conversa! tional strategies to collaborate and co-participate with their interlocutors.