Welcome to the Eighth International Conference on Knowledge Capture - K-CAP 2015. The goal of K-CAP is to highlight research on the extraction of useful knowledge from diverse sources: unstructured information sources, semi-structured and structured data sources, knowledge graphs and directly from crowds and individuals, either through observation or implicit or explicit elicitation. The wealth of information available from such a variety of sources calls for new methods of Knowledge Capture that draw both from traditional knowledge acquisition techniques and from more data-driven techniques such as large-scale data mining, statistical analysis and data analytics. Researchers and practitioners who work in the area of Knowledge Capture traditionally participate in several distinct communities, including Knowledge Engineering, Machine Learning, Natural Language Processing, Human-Computer Interaction, Artificial Intelligence and the Semantic Web. K-CAP 2015 provides a forum to bring together members of disparate research communities who are interested in all aspects of capturing knowledge from a variety of sources, as well as those interested in creating representations that can be useful for reasoning, analysis, and other forms of machine processing.