This article reviews how practical work, including practical skills, is currently summatively assessed in school science in a number of countries and makes comparisons with how other subjects, such as music and modern foreign languages, summatively assess skills. Whilst practical skills in school science are clearly valued as being of importance, there is a lack of clarity as to what these skills actually are and how they might, most effectively, be validly assessed. Countries vary greatly in the extent to which they employ what we term "Direct Assessment of Practical Skills" (DAPS) or "Indirect Assessment of Practical Skills" (IAPS). Each of these approaches has advantages and disadvantages but we conclude that too great reliance on IAPS reduces the likelihood that practical work will be taught and learnt as well as it might be.