This study demonstrates the importance of including narrative ethics in a construction of Old Testament ethics. The social identity approach is used as a lens through which to understand and derive ethics. This approach highlights the social emphases of a biblical text, and consequently assists in understanding a text's original ethical message. This book of "Ruth" is used as a test case, employing a social identity approach for understanding the narrative, but also to model the approach so that it can be implemented more widely in study of the Old Testament and narrative ethics. Each of the protagonists in the book of "Ruth" is examined in regards to their personal and social self-components. This study reveals that the narrative functions to shape or reinforce the identity of an ancient Israelite implied reader. A social identity approach can also highlight the social processes within a society. The social processes taking place in the Monarchic and Persian Periods are discussed, and it is found that the social emphases of the book of "Ruth" most closely correspond to the social undercurrents of the Persian Period.