This paper argues that a barrier to union organizing is the identification of workplaces in which the union voting propensities of workers are sufficient to justify an organizing drive. It also argues that prior research into these propensities has been of limited value in this respect. It then draws on a unique telephone survey of Canadian workers to explore the implications of a variety of individual-, work-, and employment-related variables for the propensity of non-union workers to vote in favor of union representation. In so doing, it proceeds from a “union organizing” perspective, seeking not just to establish whether these variables appear to “cause” voting propensity, but also whether they are correlated with it, and hence serve as markers for union organizing, and if so, how and why they do. It also seeks to demonstrate the possible value of survey research and hence encourage a more scientific approach to union organizing choices. A wide array of variables is found to have potential implications for these choices.