The present invention concerns antigen binding proteins that bind TL1A, including bispecific antigen binding proteins (e.g., antibodies) to TL1A and TNF-α. Such bispecific antibodies can be in a tetrameric immunoglobulin format, in which one heavy chain-light chain pair of the antibody is directed to TL1A and the other to TNF-α. The bispecific antigen binding proteins may also be comprised in an IgG-scFv fusion, in which a conventional tetrameric antibody directed to one antigen is fused to a pair of single chain Fv units directed to the other. The bispecific antigen binding protein may also be comprised in an IgG-Fab fusion, in which a Fab molecule that binds to one antigen is fused to each heavy chain of a conventional tetrameric antibody directed to the other antigen. The invention further relates to uses of the anti-TL1A binding proteins and anti-TL1A/anti-TNF-α antigen binding proteins, and pharmaceutical formulations thereof.