(-) Practical issues- original label must be false according to theory, and so in naturalistic studies, self-report measures used to establish label was false, which require participants to be open and honest - may not do so due to demand characteristics or social desirability bias, unethical to give participants a false label, as may damage their self-esteem. Cannot establish cause and effect and be sure manipulation of IV, negative labelling, is causing change in DCV, criminal behaviour, reducing validity of self-fulfilling prophecy as an explanation for criminal behaviour