The main objective of this work was to investigate two testing procedures, repeated static tests and dynamic testing, that can more clearly demonstrate the impact of treatment for parasites in children. Rural Tanzanian children were assessed for the presence/absence and burden of helminth parasites and assigned to one of three groups—infected/treated with anthelmintic medication, infected/not treated, and uninfected/not treated. All three groups were assessed with dynamically administered cognitive tests (on three separate occasions, with each session including pretest, instruction, and posttest), conventionally (statically) administered cognitive tests, and traditionally administered educational achievement tests. The data demonstrated that the children in the infected/treated and uninfected groups showed higher cognitive gains on two out of three dynamically administered and one out of eight statically administered tasks than did the children in the infected/not treated group. Thus, anthelmintic medications for parasitic illnesses appear to contribute to the improvement in cognitive functioning and this improvement is captured more clearly in dynamic than static tasks. The pathways of this improvement are still not understood and require further investigation.