The TOWA is a two-staged, criteria-based assessment of a piece of writing completed under test conditions. 
The writing is assessed against the following criteria:
- Thought and ideas (quality of analysis, response and presentation of information or issues); and
 - Language: Structure and expression (effectiveness of structure and organisation, clarity of expression, control of language conventions).
 
There are three described levels of achievement for each criteria.
- In addition, Control of language conventions, a sub-set of language , is further assessed on the following characteristics:
 - Paragraphing
 - Syntax, grammar, sentence fluency
 - Vocabulary
 - Spelling conventions
 - Punctuation conventions.