This document provides an overview of non-parametric tests in SPSS, specifically the Mann-Whitney U test and Kruskal-Wallis H test. It describes when to use non-parametric tests, the SPSS procedures for the Mann-Whitney U and Kruskal-Wallis tests, and how to interpret and report the outputs of these tests. Examples are given of using these tests to compare criminal thinking between violent and non-violent offenders and to compare psychoticism between prisoner age groups.