Whilst the presence of earthworms is used by many farmers as a general indicator of soil health, measurement is generally subjective. The chapter reviews current challenges in collecting more systematic and reliable data on earthworm communities, including issues in identifying epigeic, endogeic and anecic earthworms groups inhabiting different soil levels. It includes a case study on developing a robust method for accurate measurement of earthworm communities in soil in assessing and improving soil health.