The present paper describes a general programme for the Ferranti ' Mercury ' Computer, whereby the stresses in folded slab roofs may be computed. The programme is automatic once the relevant dimensions and loads on the folded slab structure (which are punched on a data tape) have been fed into the computer; the output (on paper tape) gives the required moments and forces at selected points across the entire structure. The programme allows the incorporation of edge beams at each junction of the individual slab elements of the structure and allows up to twelve individual slab elements forming the composite structure to be analysed. The number of slab elements allowed in the structure is not limited by the nature of the programme but by the storage capacity of the machine. In a more recent programme in which edge beams have been eliminated, as is more often the case in such folded structures, making available storage space previously occupied by the edge beam routine, many more slab elements per structure may be allowed. However for the purpose of this paper, the programme in its original form will be discussed, and examples of some typical structures will be given. The geometrical disposition of the individual slab elements may be varied as desired.