Disclosed herein are methods for joining one piece to tissue to another piece of tissue. In one embodiment, the method can include inserting an applier device having an actuation portion into a first body lumen through a natural body orifice, forming a first opening in a first piece of tissue within the first lumen and a second opening in a second piece of tissue defining a portion of a second lumen adjacent to the first piece of tissue, and inserting the applier device through the first and second openings such that the actuation portion is between the first and second piece of tissue. The method can further include deploying a fastener into the first and second pieces of tissue through the actuation portion of the applier device, thereby joining the first and second pieces of tissue to form an anastomosis between the first and second lumens.