Improvement of animal welfare first requires that we develop objective measures to enable us to compare and contrast the implications of husbandry procedures or housing options.  Such measures need to be versatile, relevant, reliable, relatively economic to apply, have broad acceptance to all stakeholders, and have little impact on the welfare of the animals themselves.  The overall demeanour or body language of animals can reflect aspects of their affective state.  Therefore, holistic qualitative measures of behavioural expression can be used to characterise the dynamic relationship between animals and their environment.  Qualitative assessments are what good animal handlers do every day as part of their core business, but these measures can also allow us to carry out comparative, hypothesis-driven evaluation of various industry-relevant practices.  In this talk, I will use the example of comparing various environments for piglets and sows, to contribute to our understanding of how modifications to housing can benefit pig welfare.