This study examines elementary students' abilities to conduct science inquiry through their participation in an instructional intervention over a school year. The study involved 25 third and fourth grade students from six elementary schools representing diverse linguistic and cultural groups. Prior to and at the completion of the intervention, the students participated in elicitation sessions as they conducted a semistructured inquiry task on evaporation. The results indicate that students demonstrated enhanced abilities with some aspects of the inquiry task, but continued to have difficulties with other aspects of the task even after instruction. Although students from all demographic subgroups showed substantial gains, students from non-mainstream and less privileged backgrounds in science showed greater gains in inquiry abilities than their more privileged counterparts. The results contribute to the emerging literature on designing learning environments that foster science inquiry of elementary students from diverse backgrounds. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 607–636, 2006