Since the 2019-2020 school year, the Plainville High School World Language Department has proudly offered opportunities for students to earn the Connecticut Seal of Biliteracy. The Connecticut State Seal of Biliteracy was established in 2017 to recognize public high school graduates who have attained a level of proficiency in English and one or more languages which includes American sign language and any other language spoken by a federally recognized Native American tribe.

The seal of biliteracy recognizes the value of students' academic efforts, the tangible benefits of being bilingual and biliterate and prepares students to be 21st century global citizens in a multicultural, multilingual world. The seal of biliteracy acknowledges that mastery of two or more languages is a valuable asset for both individuals and their communities. Additionally, the seal of biliteracy provides recognition to English language learners for the great value of developing English and maintaining their primary language. 

Proficiency in a World Language is determined through scoring on one of several state approved assessment tools such as the Oral Proficiency Interview (OPI), the LAS links, or the Advanced Placement Exam. All available tests measure listening, speaking, reading, and writing proficiency.  For students whose non-English language is low incidence and proficiency is not easily attainable (no assessment available) the district will conduct an interview to determine how such language was acquired and developed throughout the student's life.

Students meeting the criteria for biliteracy receive a seal affixed to their diploma and to their high school transcript and will also be given a medal to wear at graduation.

The marker is affixed to diplomas and is  useful to both employers and to colleges and universities. It helps to identify students with verified multilingual skills.