Knowledge graphs (KGs) have recently emerged as a powerful way to represent knowledge in multiple communities, including data mining, natural language processing and machine learning. Large-scale KGs like Wikidata and DBpedia are openly available, while in industry, the Google Knowledge Graph is a good example of proprietary knowledge that continues to fuel impressive advances in Google's semantic search capabilities. Yet, both crowdsourced and automatically constructed KGs suffer from noise, both during KG construction and during search and inference. In this talk, I will discuss how to build and use such knowledge graphs effectively, despite the noise and sparsity of labeled data, to solve real-world social problems such as providing insights in disaster situations, and helping law enforcement fight human trafficking. I will conclude by providing insight on the lessons learned, and the applicability of research techniques to industrial problems. The talk will be designed to appeal both to business and technical leaders.