This document summarizes the current status and ongoing developments in wind turbine blade standards. It discusses legacy blade standards and the introduction of IEC 61400-5, which aims to establish a "physics-based" approach to safety factors using a "limit states" design methodology. The primary technical challenges include moving beyond two-dimensional analyses to fully 3D finite element analyses and using probabilistic methods rather than classical safety factor approaches. The drafting process for IEC 61400-5 has taken over six years and aims to reward "responsible innovation" by relating partial safety factors more directly to uncertainties.