This chapter analyses the impact that tax practitioners potentially have on the tax compliance environment. Until relatively recently, taxpayer compliance research (see Richardson and Sawyer (2001) for an exhaustive review) did not consider the potential impact of the tax practitioner on the compliance decision. We review existing research on the role of the practitioner around three major issues: 1) the demand for tax preparation services, 2) the factors that affect practitioners’ compliance decisions, and 3) the compliance level of returns filed with assistance from practitioners.