This paper describes how a Many Faceted Rasch Measurement (MFRM) approach can be applied to performance assessment focusing on rater analysis. The article provides an introduction to MFRM, a description of MFRM analysis procedures, and an example to illustrate how to examine the effects of various sources of variability on test takers' performance on a writing test by means of a MFRM analysis. Results highlight the usefulness of the MFRM to detect raters that have extreme values on the severity continuum. MRFM provides a common metric for the facet scores (test takers, tasks, raters). This is advantageous because it facilitates understanding of the assessment process as well as providing objective measurement of facet elements.