There are many laboratory biofilm models available which can be used to assess the susceptibility of these distinctive resistant phenotypes. The complexities of these models vary considerably and indeed, the antimicrobial susceptibility of biofilms grown in these different models are also not standardised. It is clear that such methods are necessary for the testing of antibiotics and antimicrobial agents since these persistent communities are far more resistant than their planktonic counterparts. Therefore, it is now apparent that standardised tests such as MIC are no longer appropriate on their own to fully characterise susceptibility. There has also been a growing realisation that bacteria are growing as biofilms in almost every health-care setting and are, thus, a major contributing factor to the difficulty of treating infections. There is a pressing need for the models outlined in this chapter to test both current and novel anti-biofilm compounds and materials.