The present invention provides anti-MASP-1 (mannan-binding lectin (MBL)-associated serine protease 1) antibodies and methods of using the same. In some embodiments, an anti-MASP-1 antibody of the invention binds to MASP-1 but does not bind to MASP-3. The invention also provides nucleic acids comprising a nucleotide sequence encoding an anti-MASP-1 antibody of the present invention. The invention further provides pharmaceutical compositions comprising an anti-MASP-1 antibody of the present invention and a pharmaceutically acceptable carrier.