This paper presents the findings of an experimental study on the use of Infrared Thermography for nondestructive evaluation of subsurface delaminations in Fiber Reinforced Polymer (FRP) composite bridge decks and concrete columns wrapped with FRP jackets. Composite bridge deck specimens were constructed in the laboratory with varying delamination sizes. The infrared images from the delaminated specimens were compared with undamaged specimens to study the effect of subsurface delaminations on the infrared images. In addition, field tests were conducted using infrared thermography on composite structural members of three bridges located in West Virginia.