The ability to work with professionals from other disciplines to deliver collaborative, patient-centred care is considered a critical element of professional practice requiring a specific set of competencies. However, a generally accepted framework for collaborative competencies is missing, which makes consistent preparation of students and staff challenging. Some authors have argued that there is a lack of conceptual clarity of the "active ingredients" of collaboration relating to quality of care and patient outcomes, which may be at the root of the competencies issue. As part of a large Health Canada funded study focused on interprofessional education and collaborative practice, our goal was to understand the competencies for collaborative practice that are considered most relevant by health professionals working at the front line. Interview participants comprised 60 health care providers from various disciplines. Understanding and appreciating professional roles and responsibilities and communicating effectively emerged as the two perceived core competencies for patient-centred collaborative practice. For both competencies there is evidence of a link to positive patient and provider outcomes. We suggest that these two competencies should be the primary focus of student and staff education aimed at increasing collaborative practice skills.