Mental state talk involves words that describe the mental world of individuals. These could be words that are about thoughts, feelings, desires, intentions, and emotions. There has been dearth of research in Pakistan assessing the parents and teachers’ use of mental state talk in conversation with young children, commonly because of lack of assessment tool that are employed to measure the mental state talk in Pakistan. The present study aimed at validation and development of indigenous tool for the assessment of mental state talk of parents/teachers to use with children. Wordless picture story book reading was selected as one the various methods devised for mental state talk assessment; which facilitates interactions between parents/teachers and their children. For validation, Indigenous picture story books were reviewed for its content and modified through opinion of subject matter experts. Content and face validity of the story book were examined and found to be good. The finding concluded that finalized wordless picture story book has rich mental state content and has great potential to stimulate rich discourse on mental state talk. It will bridge the research gap and will promote as a good measurement instrument for research on mental state talk in Pakistan.