This book was worth the purchase because of the leveled word lists for ALL subjects. Almost 8,000 for 11 subjects - that includes all the topics covered in Social Studies, noncore classes, all leveled by grade range.
It does refer to the accompanying Marzano work often and I found I needed to purchase both to receive the full amount of understanding I wanted on the subject.
You need this if you are wondering how to start a vocabulary program. You would be interested in the list if you already have a vocabulary program.