Architectural design teaching using computers has been a preoccupation of CECA since 1991. All design tutors provide their students with a set of models and ways to form, and we have explored a set of approaches including cellular automata, genetic programming,agent based modelling and shape grammars as additional tools with which to explore architectural ( and architectonic) ideas.This paper discusses the use of genetic programming (G.P.) for applications in the field of spatial composition. CECA has been developing the use of Genetic Programming for some time ( see references ) and has covered the evolution of L-Systems production rules( coates 1997, 1999b), and the evolution of generative grammars of form (Coates 1998 1999a). The G.P. was used to generate three-dimensional spatial forms from a set of geometrical structures.The approach uses genetic programming with a Genetic Library (G.Lib).G.P. provides a way to genetically breed a computer program to solve a problem.G. Lib. enables genetic programming to define potentially useful subroutines dynamically during a run.* Exploring a shape grammar consisting of simple solid primitives and transformations. * Applying a simple fitness function to the solid breeding G.P.* Exploring a shape grammar of composite surface objects. * Developing grammarsfor existing buildings, and creating hybrids. * Exploring the shape grammar of abuilding within a G.P.We will report on new work using a range of different morphologies ( boolean operations, surface operations and grammars of style ) and describe the use of objective functions ( natural selection) and the “eyeball test” ( artificial selection) as ways of controlling and exploring the design spaces thus defined.