This paper presents a survey of the issues and methods for the association and fusion of data from multiple sensors. It will cover three broad areas. The first, data association, refers to the problem of partitioning the sensor data into tracks according to source. We next discuss the techniques used for kinematic and attribute estimation after data association has been performed. In particular, we will discuss the philosophies associated with alternative techniques for attribute and target type estimation, with an emphasis upon the Dempster-Shafer approach. The third major topic discussed is sensor allocation.