A critical analysis of the stability of return-to-contour backfills with regard to slope failure was conducted at 4 apparently unstable sites in SW Virginia. Our goal was to identify the major factors contributing to slope instability. Investigations included detailed site surveying, slope monitoring, and spoil sampling. Shear strength parameters were measured on spoil material recompacted to approximate field density conditions by consolidated-drained direct shear testing to evaluate effective strength parameters. Slope stability was calculated by the simplified Bishop method using the REAME (Rotational Equilibrium Analysis of Multilayered Embankments) computer program. Where appropriate SWASE (Sliding Wedge Analysis of Sidehill Embankments) was used to evaluate sliding wedge failures.