It is important to know the race and culture that a client comes from as a social worker. As a professional you follow professional guidelines of conduct which guide you to ensure you follow ethical practice. Part of this is having an understanding of cultural differences in the clients that you work with to help to ensure clear communication and fair treatment. Each cultural group has different guidelines in regards to expectations of behavior and it is important to understand what these guidelines are so that behavior is not misinterpreted and unfairly penalized. For example, it is common in the Native American culture not to look a person in the eye when you are talking to them as a sign of respect. However if you come from a culture where it is important to look someone in the eye to show you are being honest, this could be interpreted as dishonesty. Having the knowledge of the cultural values of a group of people you are working with prevents this misjudgement from happening.
Additionally it is important to understand how the client's micro system works, which will vary from ethnic group to ethnic group, and what their experience with the macro system may be, which may also vary from group to group.