Licensing the Lexile PowerV Vocabulary API & Service

What is the Lexile PowerV™ vocabulary API and service?

The Lexile PowerV vocabulary API and service uses a book or piece of text to develop a vocabulary list that contains challenging words that a student should know when reading a book. This technology can be used by education companies to build differentiated instruction capabilities into their reading and vocabulary program. It is available as an API or as an add-on service for text measurement. To learn more about Lexile PowerV, view our recorded informational webinar.

How does the Lexile PowerV technology work?

Lexile PowerV uses a book or piece of text to select words that will be challenging, relevant, and consequential to a student when reading a book. Lexile PowerV uses the following criteria to determine which words are most important for a student to know.

1. Using the Lexile scale, harder words are identified by selecting words that are above the Lexile measure of the text.

2. The consequence and relevance of the words are considered. To determine this, a combination of factors are examined including:

  • How important is a word to the text? Words that appear more frequently in this particular book than in texts generally are identified. These are words that are important for understanding the main themes and topics in the text.

  • What is the size of the word family? Words that have a number of prefixed and suffixed forms are identified. These are words that allow students to apply word knowledge to several other forms of the word and help them expand their vocabulary.

  • On how many word lists is the word included? Words that appear on other word lists are identified. These are words that are academic and important for success in school.

What is the research behind Lexile PowerV?

Lexile PowerV is a result of years of research evaluating the complexity of over 75,000 words and developing an algorithm to place these words on the Lexile scale. Below are the research briefs summarizing the research behind Lexile PowerV.

How do I license Lexile PowerV?

Two licensing options are available:

1. The Lexile PowerV technology is available as a convenient API (Application Program Interface). With the Lexile PowerV API:

  • Vocabulary lists can be generated for a large quantity of texts.

  • Vocabulary lists can be generated at specific Lexile ranges from a piece of text.

  • Vocabulary lists from over 125,000 titles can be accessed when used with the Lexile® Titles Database.

To receive a quote for the licensing fee of the Lexile PowerV API, please contact Trilby Berger, Senior Vice President of Strategic Partnerships, at

2. Lexile PowerV is also offered as an add-on service for Lexile text measurement. By using this add-on, a Lexile PowerV vocabulary list (up to 20 words) will be returned with your certified Lexile text measure. The add-on service fee is $10 per book.

To request Lexile PowerV vocabulary lists for your titles, contact Bryan Brammer, Publisher Relations Manager, at