Chronic widespread pain (CWP) is common and associated with loss of functioning and health. Subjects with chronic non-widespread pain (CnWP) are at increased risk of developing CWP, but few studies have described the nature of the development over time.We followed a random sample of 3105 participants from the population-based HUNT-3 study with five annual measurements of pain over four years. While 29% reported CWP on at least one occasion, only 7% reported it consistently on four or fsive occasions. The average annual cumulative incidence was 5% and the recovery rate was 38%. In mutual adjusted analysis, the risk of developing CWP from one year to the next was higher in subjects with chronic pain (RR=2.4; 95% CI: 1.8-3.4), two or more pain regions (RR= 3.3; 95% CI: 2.5-4.4), moderate pain or more (RR=1.8; 95% CI: 1.5-2.6) and with comorbid chronic disease (RR=1.6; 95% CI: 1.3-1.9). Developing CWP was associated with a modest concurrent change in self-reported mental and physical health. The risk of developing CWP between the fourth and fifth occasions was 80% lower for subjects without a history of CWP, compared to those with. For subjects without previous CWP, the development was associated with previously reported CnWP, but not with the number of occasions with CnWP, in analyses adjusted for sex, age and pain severity.A substantial proportion of the new cases of CWP originates from subjects floating below and above the definition for CWP over time, and thus, do not seem to involve major transitions in health.