Psychologists, by the very nature of their work, are faced with practicing at the borders of their competence, for two reasons. First, they may encounter certain clients or situations for which they are only minimally prepared; and second, as human beings they are subject to the same destructive effects of untoward life events as their clients, despite a tendency to consider themselves immune. There are at least three ways of practicing outside one's areas of competence: (1) accidental--practice beyond one's competence; (2) deliberate practice beyond one's competence; and (3) failure to use community resources. Therapist impairment can be defined as compromised judgment, competence, or ability to carry out professional activities as they directly or indirectly affect others. Frequently, the cause of such impairment is a series of significant life events, as viewed by an objective observer, though the psychologist may not always be aware of the toll which has been taken. To avoid the pitfalls of practicing beyond one's area of competence, therapists should improve their diagnostic and treatment skills; refuse to accept certain clients for whom they are not well prepared to treat; know personal danger schedules and monitor one's own mental health; consult a senior colleague when in doubt; limit one's practice as necessary; belong to an ongoing professional peer group; and be current and familiar with the state-of-the art. The return on the investments of time and money in these areas is immense, including expanded professionalism, reduced risk of ethics complaints, and a higher quality of service. (ABL)