The following characteristic phases in joint behaviour under shear forces can be distinguished: phase I—joint as monolithic structure (bond not damaged); phase II—when the bond is damaged. This phase decides the joint bearing capacity, and deformability and its effect on the behaviour of the whole shear wall. For the calculation of the bearing capacity of shear-key joints two formulae have been proposed by the author. The first formula concerns the failure state of a joint which which is not diagonally cracked. The second formula refers to the failure state of a diagonally cracked joint. The proposed formulae were verified on the basis of experimental data obtained from tests by Hansen and Oleson, Pommeret and the author. Correction factors were found from the tests and a final formula embodying these factors is proposed for the calculation of the bearing capacity of joints. The influence of basic structural parameters has been analyzed and discussed on the basis of experimental results. These parameters are cross-sectionel area of keys, ratio of reinforcement and shape of keys. Minimum reinforcement ratios are proposed and a comparison of various national standard regulations concerning joint bearing capacity is presented.