Interior Architecture bridges the practices of interior design and architecture so that professionals working in the field have a structural and load bearing education with an emphasis on interior spaces. The field is similar to architecture in that it deals with structures and load bearing walls. It is similar to interior design in that it focuses on interior spaces.
The National Center for Education Statistics's definition of Interior Architecture: "A program that prepares individuals to apply architectural principles in the design of structural interiors for living, recreational, and business purposes and to function as professional interior architects. Includes instruction in architecture, structural systems design, heating and cooling systems, occupational and safety standards, interior design, specific end-use applications, and professional responsibilities and standards."
In the United States, what is considered "interior design" is called "interior architecture." However, a practicing professional cannot use the title of "Interior Architect" unless they complete the requirements for becoming a licensed architect.
In mainland Europe (that is excluding the anglo-saxon countries) the term "Interior Architecture" is generally used. In many European countries the use of the title "Interior Architect" is legally regulated. For more information see ECIA.