Overweight/obesity and pain are significant problems of increasing prevalence; understanding the relationship between the two is the focus of a growing body of research. Findings from this review support a likely relationship between increasing weight and pain conditions such as osteoarthritis and low back pain. Longitudinal studies suggest overweight/obesity early in life is a risk factor for pain, and the co-occurrence of pain and overweight/obesity negatively affects quality of life. The mechanism of relationship is unknown but is hypothesized to include mechanical and metabolic abnormalities, possibly secondary to lifestyle choices. Observations from a few studies demonstrate that treatments for obesity reduce pain secondary to weight loss. Few studies examine both pain and weight as primary outcomes, and variability in measurement makes comparisons and conclusions difficult. Research should focus on expanding knowledge about mechanisms of the relationship between pain and obesity, testing explanatory models addressing their co-occurrence, and developing treatments that most effectively target this comorbidity.