The present invention provides antibodies that bind to the T cell co-inhibitor lymphocyte activation gene 3 (LAG3) protein, and methods of use. In various embodiments of the invention, the antibodies are fully human antibodies that specifically bind to LAG3. In some embodiments, the antibodies of the invention are useful for inhibiting or neutralizing LAG3 activity, thus providing a means of treating a disease or disorder such as cancer or viral infection.