Objectives: Short leg length has been associated with increased disease risk. We investigated (1) whether taller childhood stature predicts longer adult leg than trunk length; (2) the effects of early life factors on adult leg/trunk length. Methods: We used data from the 1958 British birth cohort on height in childhood and at 45 years, leg and trunk length at 45 years and early life factors (n≈ 5,900). Results: For a SD increase in height at 7 years, adult leg length increased more than trunk length (2.5–2.8 cm vs. 1.9 cm). Parental height had a stronger association with adult than childhood height, and leg than trunk length. Prenatal factors were associated with leg (maternal smoking) and trunk length (birth order); birth weight had a similar effect on leg and trunk lengths. Large family size, overcrowding, and social housing were more strongly associated with leg than trunk length: deficits in adult height (0.4–0.8 cm) were mostly due to shorter legs. Conclusions: Socio-economic adversity in childhood is associated with delayed early growth, shorter adult leg length, and stature. Leg length is the height component most sensitive to early environment. Studies of early life and adult disease could usefully assess adult leg length in addition to height. Am. J. Hum. Biol., 2007. © 2007 Wiley-Liss, Inc.