The most widely used classification of ESG investment strategies was proposed by the Global Sustainable Investment Alliance (GSIA) in 2012，which includes Negative/exclusionary screening, Best-in-class/positive screening, Norms-based screening, ESG integration, Sustainability themed/thematic investing, Corporate engagement & shareholder action, Impact investing and community investing. The largest ESG investment strategy globally is ESG integration, with a combined USD25.2 trillion in assets under management. The next most commonly deployed ESG investment strategies include negative/exclusionary screening (USD15.9 trillion) followed by corporate engagement & shareholder action (USD10.5 trillion).
 
Negative/exclusionary screening: The exclusion from a fund or portfolio of certain sectors, companies, countries or other issuers based on activities considered not investable.Exclusion criteria (based on norms and values) can refer, for example, to product categories (e.g., weapons, tobacco), company practices (e.g., animal testing, violation of human rights, corruption) or controversies.
Best-in-class/positive screening: Investment in sectors, companies or projects selected for positive ESG performance relative to industry peers, and that achieve a rating above a defined threshold.
Norms-based screening: Screening of investments against minimum standards of business or issuer practice based on international norms such as those issued by the UN, ILO, OECD and NGOs (e.g. Transparency International).
ESG integration: The systematic and explicit inclusion by investment managers of environmental, social and governance factors into financial analysis.
Sustainability themed/thematic investing: Investing in themes or assets specifically contributing to sustainable solutions - environmental and social - (e.g., sustainable agriculture, green buildings, lower carbon tilted portfolio, gender equity, diversity).
Corporate engagement & shareholder action: Employing shareholder power to influence corporate behaviour, including through direct corporate engagement (i.e., communicating with senior management and/or boards of companies), filing or co-filing shareholder proposals, and proxy voting that is guided by comprehensive ESG guidelines.
Impact investing and community investing:

Impact investing: Investing to achieve positive, social and environmental impacts - requires measuring and reporting against these impacts, demonstrating the intentionality of investor and underlying asset/investee, and demonstrating the investor contribution.
Community investing: Where capital is specifically directed to traditionally underserved individuals or communities, as well as financing that is provided to businesses with a clear social or environmental purpose. Some community investing is impact investing, but community investing is broader and considers other forms of investing and targeted lending activities