The main goal of this paper is to analyze and investigate sustainable practices in small and medium-sized manufacturing enterprises (SMEs). A comprehensive analysis and a mathematical framework are used to assess the sustainability indexes (SDIs) of each aspect/issue and pillar/dimension, and of the whole manufacturing enterprise. Sustainability in the whole manufacturing enterprise is represented by the sustainable development index (SDI). The results show that there is a significant difference in SDIs between aspects and dimensions, with economic sustainability representing the highest percentage in the SDI. Also, the results show that industrial companies are adopting sustainable practices and applying them to most of the issues/aspects of the dimensions, and they can direct manufacturing companies in the industrial sector to develop strategies for sustainability. This paper introduces a new understanding of the practices and implementation of sustainability/sustainable development by SMEs through assessing the SDIs.