The methods used to produce the projections divide the inmate population into about 30 subsets on the basis of type of custody, age, and length of sentences. For most of the subsets, projections of historical series on the number of persons received are produced and then converted to projections of populations on the basis of average time spent in custody. For some of the smaller subsets and historical population, data are projected directly. Demographic factors provide a reliable projection of the age and sex composition of the general populations. Changes in policy and practice that impact on the size of prison population include reduction in sentence lengths, partly suspended sentences, new sentence structure for young offenders, restrictions on parole, decrease in receptions from magistrates courts, and change in mode of trial for certain offenses. On the bases of these methods and assumptions, the projections for 1999 include total population increases of about 10,600 to 11,300; a decrease in male young offenders from 6,100 in 1990 to between 4,900 and 5,400; an increase in sentenced adult male population by 7,500 to 35,000; and an increase in the remand population from 9,900 in 1990 to between 14,300 and 14,600. The projections for the total prison population for 1998 are between 1,600 and 1,700 lower than those published in October 1990.