The Kidskin Study is a 5-year intervention study (1995-1999) involving 1,776 5- and 6-year-old children attending 33 primary schools in Perth, Western Australia. The aim of the study is to design, implement, and evaluate an intervention to reduce sun exposure in young children. There are three study groups: a control group, a "moderate intervention" group, and a "high intervention" group. The control schools receive the standard Western Australian health education curriculum, while the moderate and high intervention schools receive a specially designed curricular intervention. In addition, children in the high intervention group receive program materials over the summer holidays, when exposure is likely to be highest, and are offered sun-protective swimwear at low cost. The main outcome measure is the number of nevi on the back. Other outcomes include nevi on the chest (boys only), face, and arms, levels of suntanning, degree of freckling, and sun-related behaviors. At baseline, the three groups were similar with respect to nevi and freckling after adjustment for observer and month of observation. Sun exposure was slightly higher in the high intervention group. The groups were also similar with respect to most potential confounders, although they differed with respect to Southern European ethnicity and parental education.