This study attempted to describe and interpret informal staff development among 23 first grade and kindergarten teachers, and a counselor working together to create a new language arts curriculum. This report of the research includes data from 11 participants. The paper begins with a review of relevant literature covering research on staff development, change, collaboration, ecocultural theory, symbolic interaction, and instructional theory. The group perceived its main function as solving the shared problem of improving the language arts curriculum and based its actions on formal and informal discussions. The study focused on four areas: the language arts curriculum; interactional decision-making processes within the group; the group's environmental support; and professional growth of the teachers involved. Participant discussions of various language arts topics are analyzed in terms of five cognitive and three affective behaviors organized into a taxonomy of behaviors. A model of collaborative staff development, based on the data, is suggested. Among the recommendations suggested are: (1) when undergoing change, teachers should work in collaborative groups; (2) to aid formative evaluation, two types of documents should be developed to work together as a system--the first, based on the taxonomy, allows users to verify the existence of relevant behaviors in their groups, and the second provides a skeleton for a group journal; (3) research should be carried out on further information on the categories and behaviors in the taxonomy; and (4) the categories and clusters of behaviors in the taxonomy should be studied. (Contains 66 references.) (ND)