In Sweden, units specialized in counselling and telephone triage, mainly performed by nurses, has developed in Child and Adolescent Psychiatric services (CAP). This study aims at illuminating the nurses’ perceptions on what helps or hinders assessments and telephone triage. Enhanced Critical Incidents Technique was utilized. According to ECIT-standard, eight nurses were interviewed in depth, to identify factors affecting triage. The result provides a comprehensive description on what is helping and hindering while performing telephone triage. This study illuminates telephone triage in a CAP-setting, providing insight that might be useful in further enhancement or implementation of the practice.