[Excerpt] This article surveys efforts by governmental and nongovernmental organizations to assess countries' compliance with core labor standards on workers' freedom of association. The relevant standards are Conventions 87 and 98 of the International Labor Organization (ILO) and the ILO's 1998 Declaration on Fundamental Principles and Rights at Work. Part II sets out key conceptual issues, particularly the distinction between "negative" and "positive" rights. Part III discusses the challenge of generating and getting accurate information about workers' freedom of association, especially when so much subjective judgment is inherent in the effort. Part IV reviews and summarizes the work of several organizations that evaluate countries' compliance with core labor standards on workers' freedom of association. Part V offers a conclusion and recommendations.