OBJECTIVE To investigate the characteristics of those doing no moderate-vigorous physical activity (MVPA) (0 days/week), some MVPA (1-4 days/week) and sufficient MVPA (≥ 5 days/week) to meet the guidelines in order to effectively develop and target PA interventions to address inequalities in participation. METHODS A population survey (2010/2011) of 4653 UK adults provided data on PA and socio-demographic characteristics. An ordered logit model investigated the covariates of 1) participating in no PA, 2) participating in some PA, and 3) meeting the PA guidelines. Model predictions were derived for stereotypical subgroups to highlight important policy and practice implications. RESULTS Mean age of participants was 45 years old (95% CI 44.51, 45.58) and 42% were male. Probability forecasting showed that males older than 55 years of age (probability=0.20; 95% CI 0.11, 0.28), and both males (probability=0.31; 95% CI 0.17, 0.45) and females (probability=0.38; 95% CI 0.27, 0.50) who report poor health are significantly more likely to do no PA. CONCLUSIONS Understanding the characteristics of those doing no MVPA and some MVPA could help develop population-level interventions targeting those most in need. Findings suggest that interventions are needed to target older adults, particularly males, and those who report poor health.