To evaluate the performance of elementary school children on various paradigms for assessing vocabulary knowledge on-line, three studies were conducted. In the first, 173 second through eighth grade students were involved in an investigation of five approaches to vocabulary assessment: synonym in context, synonym out of context, cloze, oral recognition, and self-screening. Results revealed significant problems with the self-screening and oral recognition formats; they were therefore eliminated from the succeeding studies. A total of 184 first through fifth graders participated in the second and third studies, which further evaluated the three remaining formats. These studies also correlated the children's performance on the three paradigms with scores on a standardized measure of reading comprehension. The results suggest that no single format is superior in assessing vocabulary knowledge across all grade levels. Data from the third study also indicate lower correlations between vocabulary knowledge and comprehension ability for the second and third grades than for the fourth and fifth grades. (Author/FL)