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In this paper the elastic interaction of multiple delaminations in laminated structures subjected to out of plane loading is studied. This has been accomplished by employing beam theory approximations of elasticity. For a cantilever beam, the shielding or amplification of the energy release rate of the cracks has been determined. Important short and long range interactions between the cracks, depending on their transverse spacing, have been shown. The results are similar to those found for the interaction of cracks in infinite bodies, but with strong modification of certain characteristics due to geometry. The shielding and amplification effects strongly influence the macrostructural behavior of the beam, leading to local instabilities, hyper-strength phenomena and crack arrest. The finite element method has been used to validate the results.