This chapter provides an overview of trends in the small and medium-sized enterprises (SME) sector and in business dynamism, and offers insights, where data allow, on cross-country and cross-sectoral differences. While the general structure of the SME population in OECD countries has remained stable in the past decade, this chapter shows that dynamic changes are occurring in activities highly exposed to digitalisation, or able to capitalise on it. The chapter highlights that in recent years the majority of new enterprise entries and the resulting job creation occurred in sectors with below average productivity levels. It presents evidence that more jobs in lower-productivity activities translated into more lower-paid jobs, weighing down on material well-being. The chapter also highlights that, apart for exceptions in the services sector, productivity gaps are observed between SMEs and large firms that translate in lower pay in SMEs. The findings reveal that gaps in productivity and wages are smaller for SMEs that export, and that global value chains provide scope for technology and knowledge spill-overs but also increase competition. The chapter demonstrates that current official statistics are able to provide important insights, in particular with respect to structural heterogeneity, but also illustrates the importance of continuing to expand the statistical boundary, not least to tackle emerging issues.