The study of alternative conceptions, or interpretations of ideas which differ significantly from the accepted scientific view at any time, has made rapid progress in the last few years. A detailed review of the field is not provided, rather achievements made and challenges for the future are noted. Areas addressed include: (1) the elucidation of alternative conceptions, discussing research methodology, need to produce diagnostic tests, and major content focus (mechanics and dynamics) in alternative conception studies; (2) conceptual development in physics; (3) approaches to developing conceptions in the classroom, indicating a key activity to be the generation of cognitive conflict in the individual student; (4) curriculum design; and (5) teacher education. It is noted that researchers in the alternative conceptions field have data which shows that some trainee physics teachers have similar conceptions to those of 12-year-olds. Therefore, it is suggested that the training of physics teachers should include ample time for the trainees to articulate, confront, and modify their own alternative conceptions. In so doing they will be subject to the same treatment that they will be encouraged to give to their students. (Author/JN)