A study investigated relationships between two instructional dimensions and change in the literacy practices of adult literacy students: degree of authenticity of activities and texts in class and degree of teacher/student collaboration. Data on class activities and texts and degree of student influence on them were triangulated from teacher questionnaire, class observation, and group-student interview. Data on change in adult students' literacy practices were collected from adult literacy students by a questionnaire administered to students in their homes every 3 months for up to a year and analyzed using Hierarchical Linear Modeling. Questionnaire responses were placed on a common scale using Item Response Theory from which a change score was derived. Analysis results based on 157 students in 77 adult literacy classes revealed authenticity had a moderate effect on change in student literacy practices, shown as increased frequency of reading and writing and/or types of texts read and written. Analysis of literacy engagement and change scales revealed that the increases in types of texts involved reading and writing more texts at higher levels of discourse. Degree of collaboration had no effect on literacy practice. Qualitative analysis of student comments on the questionnaire showed they reported life changes--changes in employment, changes emanating from learning to read and write, and changes in living and family situations. (Contains 45 references.) (YLB)