The issues of confidentiality and boundaries cause ethical dilemmas for psychotherapists. We investigated whether therapists have ethical attitudes to confidentiality and boundaries that are unique to their professional group compared with lay persons and whether gender or professional characteristics are associated with these attitudes. Clinical vignettes capturing ethical dilemmas regarding confidentiality and boundaries were presented to 93 psychotherapists of different professional backgrounds (professional group) and 55 staff and students from the fields of law and the humanities (lay group). In general, the lay group showed a greater tendency to maintain confidentiality than the professional group. Regarding boundaries, the majority of psychotherapists were against initiating any sexual relationship with current patients, former patients, students, or supervisees; the differences between the groups in this area were statistically significant. The vast majority of therapists (96.7%) disapproved of accepting money in advance compared with only 54.4% of the lay group. Analysis of the psychotherapists by professional background revealed that for the majority of the vignettes, there was no difference in attitude to confidentiality and boundaries between psychiatrists, psychologists, and social workers. The present study shows that therapists have different ethical codes from nontherapists regarding the issues of boundaries and the treatment contract. Therapists are stricter than nontherapists regarding issues of boundaries but less strict regarding issues of confidentiality, and there are some minor differences in the attitudes to these issues among different types of therapists.