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The MacArthur-Bates Communicative Development Inventories (CDIs) are some of the most widely used and recommended measures of language and communication for young children.

Web-CDI is an online administration website for the CDIs. With Web-CDI, the professional can set up children, send links to parents and caregivers to complete the assigned measure, and track progress. The parent/caregiver completes the measure on a laptop or tablet with internet connection. Upon completion, the professional can download the data and results.

Four Web-CDI products are available for purchase:

  1. MacArthur-Bates Web-CDI English Access
  2. MacArthur-Bates Web-CDI Spanish Access
  3. MacArthur-Bates Web-CDI English Computer Adaptive Testing (CAT) Access
  4. MacArthur-Bates Web-CDI Spanish Computer Adaptive Testing (CAT) Access

Accessing Web-CDI

Once you have completed your purchase, you will receive an email with an access code. Please be sure to check your Junk/Spam folder. Follow the directions attached and posted here to the email to register for a Web-CDI account at and input your code. The access code will activate your account for one year.

By purchasing an access code and using Web-CDI, you agree to abide by the Terms of Use.

Customers should purchase one access code for each professional, alongside the MacArthur-Bates Communicative Development Inventories User’s Guide and Technical Manual, Third Edition for useful information about the development and use of CDI.

Learn more about the MacArthur-Bates CDIs, Third Edition here.