Transverse ply cracking and its induced delaminations at the ø/90 interfaces in […/:øi/øm/90n]s laminates are theoretically investigated. Three cracked and delaminated model laminates, one five-layer model (FLM) laminate [SL/øm/902n/øm/SR]: and two three-layer model (TLM) laminates I and II, [øm//902n/øm/] and [SL/902n SR] are designed to examine constraining mechanisms of the constraining plies of the center 90-ply group on transverse crack induced delaminations, where SL\SL, SR, SL and SR are sublaminates [.../C] [øi…] […/øi/øm] and [øm/øi/…] respectively, A sublaminate!wise _rst!order shear laminate theory is used to analyze stress and strain elds in the three cracked and delaminated laminates loaded in tension [The extension sti] ness reduction of the constrained 89-plies and the strain energy release rate for a local delamination normalized by the square of the laminate strain are calculated as a function of delamination length and transverse crack spacing[ The constraining e]ects of the immediate neighboring plies and the remote plies are identi_ed by conducting comparisons between the three model laminates[It is seen for the examined laminates that the nearest neighboring ply group of the 89-plies primarily a]ects the sti]ness reduction and also the normalized strain energy release rate\whereas the in uences of the remote constraining layers are negligible