A longitudinal evaluation of language arts and mathematics achievement for grades 5 to 8 in the St. Catharines, Ontario school system over a forty-year span is presented. The comparison is based on three different studies conducted from 1933 to 1938, from 1952 to 1954, and from 1975 to 1977. Secondary contributions--the effects of changes in relative socioeconomic status, age-grade levels, vocabulary, and school objectives--have been taken into consideration. The major conclusions are as follows: (1) Current grade 8 students achieve consistently lower than their earlier counterparts in arithmetic computation and reasoning; however, they perform as well as or marginally better in paragraph reading. (2) Today's grade 5 to 7 students outperform their earlier counterparts in fundamental operations in arithmetic. (3) The performance of grade 6 students in paragraph reading has shown a steady but small improvement over the past forty years. (4) The ability of students in grades 5 to 8 to initiate vocabulary from descriptions has sharply improved over their earlier counterparts, and reveals a much greater range of correct alternative responses. The arithmetic and language arts tests utilized in the 1975-77 studies are appended. (Author/MV)