The sustainability arena has been abuzz over the latest corporate responsibility rankings: Newsweek's Greenest Companies and The Boston College Center/Reputation Institute CSR Index.

While such assessments provide valuable insights, most are limited in informational value because they omit smaller companies (and often private and international ones).

Boston College includes only entities at the top of their sector, Newsweek evaluates the 500 largest US and 100 biggest global public corporations. The CRO 100 Best Corporate Citizens, Climate Counts and others are similarly delimited in scope. This focus is mirrored in mainstream media coverage and sustainability professionals' commentaries.

The most common arguments for centering assessments and general attention on large businesses are that they have the biggest impacts given their magnitude, and represent appropriate benchmarks for leadership.

When filters like this are applied, we're left with only a piece of bigger picture that facilitates benchmarking only across similar peers or provides guidance to a subset of the population. Moreover, we lose the opportunity to realize the many ways corporations and stakeholders can benefit by evaluating and communicating practices across industry in its full diversity.

Specific points in favor of a more inclusive, comprehensive view include:

Whenever the field of inquiry is limited, we're sure to miss many of the "best" or "greenest." There are numerous, successful smaller mission-driven enterprises that remain off the ratings radar, united in organizations like the Green America Business Network, the Social Venture Network and the Food Trade Sustainability Leadership Association (full disclosure, my part-time employer). When we screen these out, we deny recognition to worthy leaders, overlook the types of practices and commitments that are necessary to address sustainability challenges at an appropriate scale, and leave aspiring corporations with limited models for improvement.

Larger absolute size doesn't necessarily equate to a larger absolute impact. A small or medium enterprise engaged in practices such as purchasing 100 percent renewable energy or organic ingredients can yield the same absolute benefits as a larger entity engaging in the same practices at levels of 5-10 percent, which is more typical for that segment.

Next Page: Spotlighting business leaders regardless of company size.