Objectives. This study examined predictors of low back pain onset in a British birth cohort. Methods. Univariate and multivariate analyses focused on individuals who experienced onset of low back pain at 32 to 33 years of age (n=571) and individuals who were pain free (n=5210). Participants were members of the 1958 British birth cohort. Results. Incident pain was elevated among those with psychological distress at 23 years of age (adjusted odds ratio [OR]=2.52, 95% confidence interval [CI]=1.65, 3.86) and among persistent moderate or heavy smokers (adjusted OR=1.63, 95% CI=1.23, 2.17). Significant univariate associations involving other factors (e.g., social class, childhood emotional status, body mass index, job satisfaction) did not persist in multivariate analyses. Conclusions. This prospectively studied cohort provides evidence that psychological distress more than doubles later risk of low back pain, with smoking having a modest independent effect. Other prospective studies are needed to confirm these findings before implications for low back pain prevention can be assessed.