This paper provides an overview of a workshop focused on fundamental exptl. and theor. aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in Sept. 2005. The goal of the workshop was to review the current understanding of the technique and identify gaps in this understanding assocd. with exptl. implementation, model descriptions, and signal interpretation. The results of this workshop suggest that uncertainties in the understanding of this technique are sufficient to lead to large variability among model predictions from different LII models, among measurements using different exptl. approaches, and between modeled and measured signals, even under well-defined conditions. This article summarizes the content and conclusions of the workshop, discusses controversial topics and areas of disagreement identified during the workshop, and highlights recent important refs. related to these topics. It clearly demonstrates that despite the widespread application of LII for soot-concn. and particle-size measurements there is still a significant lack in fundamental understanding for many of the underlying phys. processes.