The boundary is a reality which is analysed using an approach which stresses three inter-acting factors : relations, space and time. These factors constitute the fundamental elements of a field of interactions through which the boundary and its functions are re-defined. Four models are developed and subsequently tested. A change in the boundary or in its functions may affect either the System of relations, the space factor or the time factor. The System of relations structures time and space which interact positively and negatively thus forming what might be termed a spatio-temporal envelope outside the control of the members of a society but up on which members are individually or collectively dependent. A first attempt to test the hypothesis has been made using four examples. The delimitation of a European type boundary in southern Tunisia and the modification of the Belgian-German boundary near Eupen have shown how the establishment of a new boundary or the re-defining of an existing one can affect the relational System and hence the socially operating time-structure which it determines. It has been further possible to show that changes in the fiscal function of the boundary determined by the Belgian government produced changes in the relational System and in spatio-temporal organization. The case of the Geneva region frontier similarly supports the hypothesis though it is the time structure which is modified first, followed by the space structure. Lastly the Ticinese emigration of the middle of the last century showed how the time structure could be modified first, followed by the relational System and, finally, by space.