Based on the need for, suggestions about the construction, and existing measures serving as models found in the literature both inside and outside of science education, the “Children's Science Curiosity Scale” has undergone six versions using four different samples of fifth graders. Respectable internal consistency (alpha) and test-retest reliabilities have been calculated. Concurrent validity has been demonstrated by significant positive correlations with another recognized curiosity measure, and by way of significant differences between students who were interested in science and students uncertain about interest in science. Somewhat weak predictive validity has been decided by way of significant positive correlations with students' semester science grades. Construct validity has been described and established by eight judges using six criteria, and supported through the use of factor analysis where four underlying factors were hypothesized as characteristics of science curiosity. Sex differences were also explored where significant differences were not found between the genders. Suggestions have been made concerning future attempts at instrument refinement, establishing conceptual validity, future research involving other variables, and classroom use in a variety of contexts.