Semiconductor devices are sensitive to contamination that can cause product defects and product rejects. There are many possible types and sources of contamination. Root cause resolution of the contamination source can improve yield. The purpose of contamination troubleshooting is to identify and eliminate major yield limiters. This requires the use of a variety of analytical techniques. Most important, it requires an understanding of the principle of contamination troubleshooting and general knowledge of analytical tests. This paper describes a contamination troubleshooting approach with case studies as examples of its application.