There are many ethical challenges when mental health professionals work clinically with Roman Catholic seminarians as well as with men and women in religious formation. This article highlights several of the most prominent ethical issues and challenges confronted by mental health professionals working with these clients. These topics include issues of competence in evaluating, treating, and consulting with seminarians, those in religious life, or those applying to enter religious life. Issues of informed consent must also be considered so that seminarians, religious life clients, applicants, and their religious superiors have clarity about the limits of confidentiality and who maintains the privilege of accessing client information. In addition, professional conflicts can arise when Church expectations may seem challenging to satisfy for professionals trained in a predominantly secular environment. Cultural understanding and appreciation are needed to work with clients from different ethnic and racial groups as well as different religious orders and branches within the Catholic Church. Finally, the role of mental health professionals in the determination of acceptance or rejection into religious life and for ordination is discussed.