Students from across all areas of computer science find the skills of computer science theory (CST) literacy–such as formal modeling and algorithms building–difficult or even impossible to acquire. The skills would make the students more valuable problem-solvers in their own subareas of computer science. Building students’ capacity to extensively build, critique and revise models and to do so in groups has great potential to help all CS majors achieve CST literacy. Participants will join us for group discussion of a range of student-generated conceptual models elicited from instructional prompts in the course “xTreme Theory”part of an NSF-funded educational research project. The objective of the Birds of a Feather session is to engage participants in discussing, “What makes a good conceptual model for understanding computer science theory?” The models CS students encounter in courses are conceptual in nature and sometimes exploratory in purpose, containing analogies, diagrams, mathematical notation, and drawings. Models in CST settings are typically presented didactically, as a “pattern” that students can apply to similar situations. Students are given little opportunity to formulate their own models and test for themselves whether they are useful in related settings. The formulation and exploration of conceptual models could be intermediate steps toward expressing ideas in formal, mathematical terms—steps that shed light on the internal mental models each student uses in such a mathematization process. Conceptual models can be iterative, where feedback from peers or an instructor can lead to revision, and reflection can lead to understanding.