I examined the effects of vocabulary instruction in theme-related words on students' knowledge of these words, knowledge about the themes, use of these words in their writing, and quality of their writing. Thirty-one third graders, identified as average and below average writers, based on their pre-intervention scores on the Test of Written Language-3 (Hammill & Larsen, 1996) participated in this study. Participants were randomly assigned to two treatment groups; an experimental that received instruction on adventure and mystery words, and a control, minimal-treatment that did not receive vocabulary instruction on these words.

     Vocabulary instruction was delivered over two consecutive weeks (six sessions) for each set of words and consisted of activities such as story reading and writing, sentence completion, vocabulary card games, and review sessions. Students in the control condition were introduced to adventure and mystery through reading and writing activities during two instructional sessions for each theme. 

The effects of vocabulary instruction were assessed using: (a) a multiple-choice vocabulary test used to assess students' vocabulary learning; (b) a story writing task used to determine whether vocabulary instruction resulted in better writing quality ratings and larger number of instructional words included in students' adventures and mysteries, and (c) a knowledge telling task where students were asked to tell everything they knew about adventures and mysteries. Additionally, a social acceptability inventory was administered to all experimental students to assess whether the instruction implemented was perceived as socially acceptable for learning adventure and mystery words.  

 Analysis revealed several statistically significant findings. Vocabulary instruction enhanced students' knowledge of adventure and mystery words taught (eta squared, 0.937 and 0.905), the use of mystery words taught in students' writing (eta squared, 0.293) and the writing quality of students' mystery stories (eta squared, 0.183). Vocabulary instruction was also perceived as socially acceptable for learning new adventure and mystery words and enhancing students' vocabulary and writing performance about both themes. More research is needed to examine the relationship between vocabulary instruction in theme-related words, knowledge about the theme, and writing about the theme. Limitations of the present study and directions for future research are also discussed.