WBCSD’s Portfolio Sustainability Assessment (PSA), first launched in 2018, can form the core of a company’s sustainability plan. The PSA offers a proven methodology for assessing a company’s product portfolio and provides a structure for decision-making.

Although the PSA is typically used as an internal company tool, external stakeholders are increasingly looking for evidence that companies make progress on their targets. This paper outlines the role that the PSA methodology and external assurance can play in building trust and providing confidence to stakeholders that a company is making meaningful progress towards more sustainable outcomes.

• Part 1 of this paper provides an introduction to the PSA and outlines the role that external assurance can provide in building trust. It discusses the various forms of assurance and provides an overview of WBCSD’s assurance maturity model.
• Part 2 provides concrete case studies that illustrate the business case for using the PSA methodology and the benefits that external assurance can provide both for processes in place and the quality of data.
• Part 3 provides a checklist to help companies assess their maturity in applying the PSA methodology.

This paper is for use by business leaders in the manufacturing and chemical sectors to enhance confidence in their companies’ portfolio assessments and engage stakeholders more effectively in their journey towards improved sustainability performance.