A Practice Note discussing pooling and servicing agreements (PSAs) which control the manner in which mortgage loans are pooled together and rated in a commercial mortgage-backed securities (CMBS) securitization. This Note describes the primary parties involved, particularly the roles of the master servicer and the special servicer, and when a loan transfers from a performing loan to a specially serviced loan. This Note further discusses certain restrictions on the use of a property if a foreclosure occurs, causing it to become real estate owned (REO) property.