The relationship between employment and retirement is changing dramatically. In contrast to an earlier pattern of relatively stable career employment leading to retirement around age 65, increasing numbers of men and women are leaving their major employment situation earlier. The process of retirement therefore takes on new meaning and duration. The segment of a person's life between stable career employment and permanent retirement at pensionable age can be quite disruptive, involving difficult job searches, employment at lower levels than before, lower wages and repeated job displacement. There is virtually no research about the effects of life course instability in mid- to late-life on health, but limited research on instability early in the working life shows that instability leads to increased mortality. The possibility that labour force instability later in life has adverse health consequences is great and merits further investigation.