Abstract: This study is concerned with an investigation into the correlation of a Number of independent variables with dependent variable of mathematics Achievement of primary five pupils in Singapore schools. For the group of Psychological factors (attitude towards mathematics, interest in mathematics, memory). two questionnaires and one digit-span test were used with 200 pupils.There were four paper-and-pencil tests developed for the other group of mathermatical factors (logical thinking ability language, mathematical concept, computational skills). Instruments were reliability tested and validated by the test-retest method, factor analysis method, KR20 and the cronbach alpha methods. Multiple correlational analysis was used to determine the results. Results showed mathematical concept with the highest correlation for all the three groups of high medium and low achievers. The correlations were both positive and significant. Stepwise regressional analysis also indicated that the group of mathematical factors contributed a higher variance to mathematics achievement that the group of psychological factors.