Socially responsible investing (SRI) represents an investment process that reflects environmental and social preferences. The financial industry is in a unique position to move corporations towards corporate sustainability. However, there is often little transparency regarding the metrics used to evaluate corporate social and environmental performance and the trade-offs involved in the evaluation. In this paper we discuss the various trade-offs of sustainability screening methodologies. We show that the rating of companies varies significantly according to whether the screening is based on toxic releases and regulatory compliance or on the quality of environmental policy and disclosure. We base our analysis on the evaluation of the performance of 15 firms in the chemical sector. The analysis indicates that firms that have the most advanced reporting and environmental management practices tend also to have higher levels of toxic releases and lower environmental compliance. We provide methodological recommendations to help stakeholders evaluate corporate environmental performance.