Inadequate assessment and management of pain among critical care patients can lead to ineffective care delivery and an increased length of stay. Nurses' lack of knowledge regarding appropriate assessment and treatment, as well as negative biases toward specific patient populations, can lead to poor pain control. Our aim was to evaluate the effectiveness of professionally directed small group discussions on critical care nurses' knowledge and biases related to pain management. A quasi-experiment was conducted at a 383-bed Magnet® redesignated hospital in the southeastern United States. Critical care nurses (N = 32) participated in the study. A modified Brockopp and Warden Pain Knowledge Questionnaire was administered before and after the small group sessions. These sessions were 45 minutes in length, consisted of two to six nurses per group, and focused on effective pain management strategies. Results indicated that mean knowledge scores differed significantly and in a positive direction after intervention [preintervention mean = 18.28, standard deviation = 2.33; postintervention mean = 22.16, standard deviation = 1.70;t(31) = −8.87,p< .001]. Post-bias scores (amount of time and energy nurses would spend attending to patients' pain) were significantly higher for 6 of 15 patient populations. The strongest bias against treating patients' pain was toward unconscious and mechanically ventilated individuals. After the implementation of professionally directed small group discussions with critical care nurses, knowledge levels related to pain management increased and biases toward specific patient populations decreased.