Final answer:
In 1988, Disability and Familial Status were added as protected classes to the 1968 Federal Fair Housing Act.
Step-by-step explanation:
The year when two additional classes were added to the 1968 Federal Fair Housing Act was 1988, and the classes that were added are Disability and Familial Status. This expansion under the Fair Housing Amendments Act of 1988 made it illegal to discriminate in housing based on an individual's disability or familial status, which includes the presence of children in the household. Specific measures were implemented to ensure that people with disabilities have equal opportunities in housing, similar to the protections afforded in employment and public programs as outlined in the Rehabilitation Act of 1973. Additionally, it required reasonable accommodations and accessibility in housing to enable individuals with disabilities to live independently.