Various embodiments of the invention provide an integrated window assembly that includes a mullion, a window frame to be secured relative to the mullion, a reinforcement member positioned within the mullion, sashes on each side of the mullion, and an integrally formed connector positioned between the reinforcement member within the mullion, the window frame, and the sashes. In various embodiments, the integrally formed connector and the reinforcement member provide improved wind resistance for the window assembly, according to various embodiments of the invention. For example, in a particular embodiment, the window assembly can withstand about 75 lbs. per square foot of pressure with no permanent deflection in excess of about 0.4%.