We identified causes of nest failure and assessed the effectiveness of predator exclosures at Piping Plover (Charadrius melodus), Snowy Plover (C. alexandrinus), and Killdeer (C. vociferus) nests in southeastern Colorado during 1994–1995. Predation, nest abandonment, and weather were the primary causes of nest failure in all three species. For any of the three species we found no significant difference in the daily survival rate between nests that were protected by predator exclosures and nests that were unprotected. We reevaluated the experimental design and data analysis of previous predator exclosure studies and identified several confounding factors, including non-random assignment of exclosures, unbalanced sample sizes between protected and unprotected nests, data pooling across years, and inappropriate statistical analyses. We suggest ways to design (e.g., randomly allocate exclosures to nests and balance sample sizes between protected and unprotected nests) and analyze (e.g., use Mayfield method) future predator exclosure studies.