Letters to the editor, one of the major ways citizens can respond to, and possibly even influence, public policy decisions, are good examples of public discourse. Those who take the time to write guest editorials or letters to the editor hope to go beyond self-expression to communication. They hope to influence the beliefs and attitudes, and even the actions, of others--to change minds. And yet, relatively few letters achieve this aim. Whatever their intent, the effect of many letters is to build not bridges but walls. Too often letter writers present a one-sided point of view and fail to empathize with those with whom they disagree. Or, writers are unwilling or unable to see beyond their own value and belief systems, making open debate of crucial issues both difficult and time-consuming. Another problem is writers' failure to adequately consider the assumptions and values of their audience. There are no simple solutions to problems as complex as these, especially since each letter is and ought to be unique. Nevertheless, there are three principles that, if followed, can lead to more effective communication: (1) consider audience and purpose carefully; (2) ground the argument, when possible, in assumptions or values shared by the audience; and (3) be specific, concrete, and--when relevant and appropriate--personal. (HOD)