Research on Trait by Treatment Interaction must become more coordinated. It should include systematic programs by individual investigators as well as those among investigators. Important factors to consider are (1) developing a clearer definition of traits which will include availability and preference as well as aptitude and ability in both the cognitive and non-cognitive domains; (2) analyzing the processes employed by learners in given learning situations rather than of the nominal characteristics of the learning situation itself; and (3) constructing theories of statement describing interlocking relations between traits, processes and environments with the recognition that these function in dynamic ways. (Author/DJ)