The theory of mind's relationship with many skills, in particular social skills, has increased the interest in evaluation these skills. The aim of this study is to develop the Test of Theory of Mind for assessing 3 -to 5-year-old children's theory of mind skills. This study has been conducted using the explanatory research model. A total of 528 children between the ages of three and five, showing typical development, with Turkish as their native language, and showing age-appropriate receptive language performance participated in the study. The children's receptive language levels were determined using the receptive language subtest from the Turkish Early Language Development Test. This study has examined the content validity, construct validity, discriminant validity, criterion validity test-retest, and internal consistency of the Test of Theory of Mind. Separate tests have been obtained for 3-, 4-, and 5-year-old children as a result of the analyses of construct validity. Each test had five subtests.The tests for 3 -and 4-year-old children each had 27 items, while the test for 5-year-old children had 26 items. The items' discrimination levels were generally very high. The tests had medium and high criterion validity. The test-retest reliability was also high for all three tests. The tests' internal consistency values were found to be high as well. Based on these results, the test has been considered as a valid and reliable tool.