This study examined effects of cultural and curricular variables on algebraic reasoning in early and middle adolescence. Four algebra curricula in England and Russia were included in the design. Two age groups were included in the samples: 10- to 14-year-olds, and 14- to 16-year-olds. Algebraic reasoning processes were examined using a written test and interviews. Profound cross-cultural and cross-curricular differences were found in students' algebraic deductive reasoning for both age groups. (Author)