The latent structure of Sense of Coherence (SOC) and its relationship with three domains of health (body function, activity and participation) were studied in a cohort of people with chronic illness (n = 771) over a period of 2 years. A structural equation approach with cross-lagged and synchronous models was applied to each combination of SOC and domain of health. Over the 2-year period SOC had enhanced body function and participation. Conversely, levels of activities as well as body function had contributed to SOC 2 years later. Significant synchronous effects were found that indicated the presence of reciprocal causation between SOC and all three domains of health. These findings challenge existing SOC theory and suggest that SOC can be considered a relevant outcome variable in chronic illness care.