Purpose: The present research tries to construct a new scale for measuring the ethical autonomy of public librarians by rereading and reinterpreting the reflections of ethical philosophers on the concept of autonomy. Methodology: This research was implemented in two phases. In the phase 1, the documentary research method and the conceptual analysis approach was used to find and analyze the key ideas of philosophers. By comprehensive search of keywords like autonomy and heteronomy among the relevant databases, books, encyclopedias and other resources, five philosophers were found who had detailed ideas about autonomy: Emanuel Kant, John Rawls, Michael Sandel, Alasdair McIntyre and Charles Taylor. In the phase 2, for the credibility analysis, the survey method was used. After constructing an ethical dilemma questionnaire based on Nicole (2008) and developing it by means of the results of conceptual analysis, 406 public librarians from among 704 librarians of Iran Public Libraries Foundation (from throughout Iran) who had passed the exam of reader’ s advisory excellence in 2016 were chosen by using the Stratified Sampling method. These librarians were chosen. The link of online questionnaire were sent to the email of these librarians and the data was gathered for analysis. For the reliability analysis, the split-half method, composite reliability and Cronbach’ s alpha were used. For the validity analysis, the Content Validity Index (CVI), convergent validity, and divergent validity (discriminant validity) were utilized. Findings: The results showed that autonomy is a concept with individual and social dimensions. It is rooted in the Kant’ s idea of autonomy (rejecting dependency to natural desires and inclinations in ethical situations), was continued in the Rawls’ s idea of justice ("remote distance from ends and living in a well-ordered society and entering in instrumental construction of the present by informed consent"), criticized by Sandel ("autonomy is reflexive construction of the self by existing with others with common goals") and McIntyre ("autonomy is doing your best to implement your social role and transcend it to an excellent condition") and paradigmatically shifted in the work of Taylor ("autonomy is to be the best actor in the realm of four fundamental ethical intuitions without infringing them"). Autonomy of different job holders like public librarians distinguishable in the ethical dilemmas and we started to measure it by constructing 22 dummy dilemmas based on 11 dimensions (integrity, fraud, cover-up, discrimination, business security, promise keeping, blackmail, manipulation, environmental security, privilege information, and pornography) in the library situations and philosophical dimensions of autonomy under dilemmas (two dilemmas for each dimension). Flexibility (on the basis of Taylor’ s idea of autonomy) was chosen as a main difference between autonomy and heteronomy and the ideas of Kant, Rawls, Sandel and McIntyre were used in order to design eight autonomous and heteronomous alternatives below each dilemma. Results of the reliability and validity analysis showed good measures except in question 18. Originality/value: The value of this research lies in its use of the philosophical dimensions of autonomy in order to study the autonomy and heteronomy in the librarians. It also can be used a new scale for measuring the autonomy and heteronomy of individulas while holding important posts.