Economist Dr. E.F. Schumacher posited the concept of "Intermediate Technology" in his 1973 book Small is Beautiful, catalyzing the explosion of the appropriate technology (AT) movement. But how does one gauge the "appropriateness" of a technology? Quantitative assessment of AT can benefit sustainable community development (SCD) practitioners by way of decision-support and risk mitigation. The following research constructs a generalizable metric for quantitative assessment of AT, and develops a systematic process for its deployment. Forty-nine independent, emergent indicators of appropriateness were identified from a literature meta-analysis. The most prevalent indicators were as follows: community input, affordability, autonomy, transferability, community control, scalability, local availability of raw materials, and adaptability. Using these, a quantitative assessment tool was developed, called the Appropriate Technology Assessment Tool (ATAT). ATAT employs multi-criteria decision analysis (MCDA) methods to rank AT alternatives. In this way, inputs are aggregated using a weightedsum method, giving the composite Appropriateness Index, ( ). Using VBA coding, the author built ATAT via a simple form populated by the identified indicators. The form automates all necessary calculations, facilitating empirically rigorous quantitative assessment of AT by non-technical SCD workers. AT is only as appropriate as beneficiaries deem. A participatory research approach requires community stakeholders to rank preferred criteria for AT, and rate alternatives against the chosen criteria. This approach makes the tool customizable to local conditions. Using the Mini-Delphi Method, stakeholder opinions translate to ATAT inputs. A local case in the Westwood neighborhood of Denver, Colorado is examined to test ATAT efficacy and process viability. Prior to this research, University of Colorado graduate students partnered with local 501(c)3 Revision International to reduce winter heating costs in Westwood using a solar furnace that locals dubbed "EZ Heat". ATAT quantified the appropriateness of EZ Heat as = 4.2. This score lends empirical support to the AT's a priori deterministic selection. ATAT is designed to be free and accessible via Internet, and the author is investigating the potential of a mobile application. SCD and other community development practitioners often work in remote areas, and a mobile ATAT application will make the tool more useful.