Background: Back pain is complex. Social support and significant other interactions influence the pain experience. Purpose: To statistically derive subgroups of people with chronic low back pain based upon their interactions with significant others, and profile subgroups across multidimensional variables. Research Design: Longitudinal cohort study. Study Sample: People with chronic axial low back pain ( n = 262). Data Collection and Analysis: Latent class analysis of significant other interaction data was used to derive subgroups of people with chronic low back pain. Subgroups were profiled across baseline multidimensional variables and one-year follow-up pain intensity, disability and bothersomeness. Results: Three clusters were identified: Cluster 1 (7.6%) characterised by the lowest distracting, punishing and solicitous interactions. Cluster 2 (16.0%) characterised by the highest distracting and solicitous responses and social support. Cluster 3 (76.3%) characterised by the highest punishing and lowest social support. Cluster 1 reported less disability than Clusters 2 and 3. Mindfulness was significantly different across all subgroups with Cluster 1 being most mindful and Cluster 3 least mindful. Depression, anxiety and stress were significantly higher in Cluster 3 than Cluster 1. Pain catastrophising was higher for Cluster 2 than Clusters 1 and 3. Cluster 2 had lower pressure pain threshold than Clusters 1 and 3. Conclusions: These results support the association between significant other interactions and the experience of back pain. Considering significant other interactions in clinical practice may be important for managing some people’s presentation.