150 application letters from the three cultural groups in Mindano, namely Sinama, Subanen, and Tausug have been analysed in a mixed–method design. The focus of the study is on the two features of politeness and intimacy. In the quantitative analysis, the model proposed by Brown & Levinson (1987) and that of Columns (2005) which have drawn upon the features of indirectness in requesting and the length of letters as the indicators of politeness are used. In the qualitative and descriptive analysis formality in salutation and opening clause as well as the use of abbreviated forms are taken into account. The result shows that Tausug use the politest style in their application letters, followed by Sinama and Subanen respectively. On the other hand, Sinama, Subanen, and Tausug use the least intimate style in their business letters. The findings are hoped to help better inter–cultural understanding, especially with respect to written rhetorical characteristics.