Mother tongue has an important place in human life. One’s mother tongue contributes a lot in thinking habits, learning of subjects and imagination etc. to any person. Students have to attain knowledge of different subjects by the medium of their mother tongue. Vernacular language has remained in root of any other language which is to be learnt, so evaluation of knowledge of mother tongue by using tests is of equal importance. Present research had been aimed at construction and standardization of the Achievement Test of Gujarati language for standard IX. Total 1586 students of standard IX studying in Gujarati medium secondary schools were selected as sample from population of students of South Gujarat. This research was undertaken using the Survey Method. Reliability coefficient of the Achievement Test was found between 0.63 and 0.98, which shows that this self constructed test is highly reliable. Content validity of the test found by Crookback Alfa was 0.88 which also shows that the constructed test is highly valid. Shape of Eigen value in construct validity was found elbow shape, which satisfies Scree Criteria, it measures only one construct and is valid in view point of construct validity.