Eastern bluebirds (Sialia sialis) commonly nest in man-made boxes, yet there have been few systematic attempts to understand how nest box design and placement influences nesting success. In this study, we monitored 411 bluebird nest boxes at 16 sites during the Summer of 2003. The nest boxes varied in their basic dimensions, were surrounded by differing vegetation types at different locations, were placed at differing densities in different sites, and varied in their proximity to roads and buildings (i.e. possible sources of human disturbance). In addition, some of the nest boxes were protected with predator guards, whereas others were not. Each week throughout the breeding season (April to August), we noted the stage of nest development. During June and July, we recorded local environmental and nest box attributes for each nest box. These attributes included: basic nest box dimensions, compass direction of the entrance hole, height of the box from the ground, type of predator guard, GPS position of the box, proximity to roads and buildings, and surrounding vegetation types. We are currently analyzing these data to describe differences between successful and unsuccessful nests.