The–Comprehensive Test of Phonological Processing (CTOPP) was published in 1999 to meet the need for an assessment of reading-related phonological processing skills. Since its initial publication, the CTOPP has been popular with professionals in psychology and education. It has been used in many studies of reading and phonological processing in both typical and clinical populations. The extent of its widespread adoption and usage is evident from the results of a recent search of the PsychInfo database for research studies using the terms Comprehensive Test of Phonological Processing or CTOPP. The query returned 4,287 results.