Data Analysis: All outcomes will be assessed following intention-to-treat principles. For each outcome, linear mixed models will be employed containing terms for participant, treatment center, group, time and group by time interaction. Known prognostic factors for increased disability in chronic neck pain will be treated as potential confounders and, in the presence of group imbalance despite random allocation, they will be treated as covariates for all outcomes. For the primary outcomes, a p < 0.05 will be considered statistically significant. For all secondary outcomes, a p < 0.01 will be considered statistically significant.