Police secrecy and inflexibility often handicap researchers, particularly in their data gathering and implementation activities. To improve data gathering, those engaged in theory-oriented research should try to persuade police to cooperate, work with police personnel least resistant to research, and approach police through influential institutions. Those engaged in applied or policy research should place the responsibility for formulating research questions and applying the results within the police department, and those engaged in normative research should publicize research objectives and find supporters within the police organization who will gather data without the police knowing about it. Police are more opposed to theory-oriented or normative research than other types of research. These researchers can overcome police reluctance by either gathering data from outside the organization or from research already conducted, or by attempting to gain police cooperation. Reference notes are included.