We present a study of the single chain elastic response for block copolymers and multiblock copolymers in selective solvents. The structures of the block copolymers are examples for the richness of single chain force extension relationships. The structure is mainly determined by the interplay of the interactions between the different blocks. Different regimes are discussed: Single micelle contributions, secondary structures, and multimicelle phases. Important contributions stem also from adsorbed bridges between different micelles in a multiblock copolymer.