In recent years, the dynamics of poverty and unemployment have come under increasing scrutiny, but another of the risks with which the welfare state concerns itself – disability – is still largely understood only in a static sense. This article uses longitudinal data from the British Household Panel Survey to investigate the complexity behind a cross-sectional snapshot. First, a breakdown is given of the working-age population who are disabled at any one time by the ‘disability trajectories’ they follow over a seven-year period. Second, the expected duration of disability for those who become disabled during working life is examined. The results show that only a small proportion of working-age people who experience disability are long-term disabled, although at any one time, long-term disabled people make up a high proportion of all disabled people. Over half of those who become limited in activities of daily living as adults have spells lasting less than two years, but few who remain disabled after four years recover. Intermittent patterns of disability, particularly due to mental illness, are common. Failing to distinguish the different disability trajectories people follow has led to policies which marginalise disabled people and are costly to the state.