The Educational Forces Inventory (EFI) charts the relative influence of 13 factors on teacher morale and classroom effectiveness. Ten general factors are: school principal; central office administrative personnel; other teachers in the school; parents; prescribed curriculum; testing programs; state legislation; physical facilities; community social environment; and curriculum personnel. Three components applicable to this sample--Project Follow Through teachers--are: program director, program advisor, and other adults in the classroom. Several hundred Follow Through teachers and teaching assistants in grades K-3 participated in a field test of the instrument, with concurrent administration of the Purdue Teacher Opinionaire (PTO). They characterized each force along two dimensions: the amount of influence it exerts upon the classroom process, and the degree to which this influence is positive or negative. The data indicated test validity: the pattern of importance ratings corresponded to independently assessed patterns of physical and social distance; the positive ratings for particular forces correlated substantially with corresponding subscores of the PTO; and the pattern of responses reflected aspects of internal consistency. Some ways of utilizing EFI data are: plotting and interpreting two-dimensional force fields, using them in program implementation, and facilitating the work of the teacher in the classroom. (Author/MH)