Using a questionnaire derived from previous research, MBA students in a semester-long negotiation course rated 30 deceptive negotiation tactics on a 7-point appropriate–inappropriate scale. Factor analysis of these ratings yielded five primary factors (replicating previous findings) representing a lay model of unethical tactics in negotiation contexts. The emergent factors are: I, traditional competitive bargaining; II, attacking an opponent's network; III, misrepresentation/lying; IV, misuse of information; and V, false promises. The five factors may be reliably measured using a 16-item questionnaire, introduced here, called the ‘Self-reported Inappropriate Negotiation Strategies Scale’, (or SINS scale). Analyses of scale ratings by participant demographics yielded some interesting results including: a tendency for women to be more averse to questionable tactics than men; a greater willingness for self-rated ‘competitive’ individuals to endorse such tactics; and differences in willingness to endorse tactics according to variables such as undergraduate major, years of work experience, and nationality. Willingness to endorse less ethical tactics did not directly relate to actual negotiation performance. Directions for future research, and further uses of the SINS scale, are discussed. Copyright © 2000 John Wiley & Sons, Ltd.