Arguing that a systems theory can be applied to the description and analysis of families and other close relationships, this paper first describes a method for coding verbal interaction that involves three steps: categorizing messages according to grammatical form and response mode, assigning control directions to those categories, and combining message control directions to form transactional types. The paper then describes the problems and choices involved in developing a method for nonverbal coding. The relational rules and patterns involved in these coding methods are described as indicants of the quality of the relationship. A methodology for integrating the verbal and nonverbal control codes is then presented for identifying and indexing relational patterns. Finally, a case study is used to relate the patterns indexed by integrating the control codes for speaker and listener to system maintenance and entropy. Transcripts of conversations from the case study and extensive tables of data are appended. (HOD)