Accurate assessment of the boundary between executive coaching and psychotherapy is essential for a successful coaching experience. The similarities between the fields of executive coaching and psychotherapy present a challenge for coaching students who have yet to master the skills required to make the assessment and create a safe and appropriate environment in which a client may reach his or her goals. This thesis describes the similarities and differences of executive coaching and psychotherapy in order to define the working space shared by the two professions. It recommends skills for coaches that include the use of self, knowledge of the coach’s and the client’s level of self-awareness, and a basic understanding of psychology. I analyze a case study as an example of a coach’s application of the tools in order to determine the boundary within an individual coaching engagement. Because it is impossible to fix an absolute boundary based on predetermined rules, I suggest that the ability to assess unique situations is a critical skill of an executive coach.