Antibodies or antigen-binding fragments thereof are engineered to bind Transforming Growth Factor-β (TGFβ). TGFβ-isoform selective antibodies or antigen-binding fragments thereof may selectively bind human TGFβ1, compared to human TGFβ2 and human TGFβ3, or may selectively bind human TGFβ3, compared to human TGFβ1 and human TGFβ2. The design of the antibodies or antigen-binding fragments thereof is facilitated by a co-crystal structure of a recombinant Fab fragment of GC1008 bound to TGFβ2 and by another co-crystal structure of the scFv version of GC1008 bound to TGFβ1.