This paper addresses the modeling of crack growth resistance of titanium-based metal matrix composites under cyclic loading by considering the conditions necessary to promote the crack arrest of dominant cracks that are often observed in these materials. The presence of dominant cracks facilitates the application of fracture mechanics parameters such as the stress intensity factor, K, and the stress intensity factor range, ΔK, to describe crack growth resistance under monotonic and cyclic loading, respectively. Using such fracture mechanics parameters, weight function methods have been used to model, assess, and predict the onset of crack arrest for cracks growing in both uniform and nonuniform stress fields. The model requires the experimental determination of crack arrest conditions for a particular testpiece geometry, for a given loading condition, and where the specific number of intact bridging fibers is also determined. It can then be used to predict the influence of crack shape and crack size for a variety of testpiece geometries and loading conditions. It is clear that corner cracks and semi-elliptical cracks are potentially more damaging than equivalent through-thickness cracks. Particular attention has also been taken to model the behavior of cracks growing in selectively reinforced composites, and the importance of the thickness of any unreinforced cladding is considered.