Do established predictors of children’s arithmetic performance differentially predict performance on timed versus un-timed calculation tests? We investigated phonological awareness (i.e., CTOPP), phonological working memory (i.e., digit span),and visuo-spatial short-term memory (i.e., Corsi blocks) as predictors of timed and untimed calculation, both concurrently inGrade 1 (N= 116) and longitudinally in Grade 2 (N = 79). Timed calculation was operationalized as single-digit addition fluencyand untimed calculation was operationalized as performance on the Woodcock Calculation subtest and KeyMath Numerationsubtest. Examined concurrently, separate multiple regressions revealed that phonological awareness predicted timed calcula-tion and all three cognitive measures predicted untimed calculation performance. Examined longitudinally, separate multipleregressions revealed that phonological awareness again predicted timed calculation and that phonological awareness and visuo-spatial short-term memory predicted untimed calculation performance. These results suggest a difference in the predictive setbetween timed and untimed calculation tests; furthermore, a difference between concurrent and longitudinal predictors.