The Teacher-Interactive Computer System (TICS) is an on-line and interactive programing system for authoring interactive programs, particularly instructional programs. The system provides a fairly natural language, in which the author's statements for creating items in a program, for examining the structure and flow, for simulating its use by students, for modifying the existing description, and for making entries in a thesaurus/encyclopedia can be intermixed homogeneously. During the authoring process, the current specification of the program is stored dynamically as a structured data base, which includes automatically generated information relating to the interdependencies among items in the program and other diagnostically useful data. Implemented in a large, general-purpose time-sharing system (Multics), the TICS authoring system is complemented by a delivery system for student use of the program. It is also intended to provide automatic conversion of completed programs to alternate formats for implementation on other computers. (Author/PB)