Incremental longitudinal shrinkage has been measured on 44 samples of Pinus radiata at each 5% increment of moisture content from 0 to 25%. The samples range in mean microfibril angle from 10° to 40°. The data is presented in the form of a family of curves, of incremental shrinkage against microfibril angle, for each moisture content. This family of curves compares very closely with those derived theoretically by Barber [1968] and Cave [1972] based on considering the cell wall as a fibre composite of cellulose microfibrils embedded in a matrix which swells on wetting and whose shear modulus is a function of moisture content.