Sustainable development is increasingly recognized for its reliance on grassroots, bottom-up practices embedded in local communities. The economic literature has tested various influencing factors on household behaviors, such as culture or social cohesion, often considering proxies of so-called “intangible capitals” separately. This article aims to jointly consider the pivotal role of three of these potential capitals that could have a trigger effect on pro-environmental behaviors, specifically, social capital (sc), human capital (hc), and institutional quality (iq). In particular, our study, by adopting a PVAR approach, analyzes if and to what extent sc, hc, and iq influence the priority goal of increasing waste-sorting practices in the 20 Italian regions. Additionally, rooted in a robust theoretical framework, we present an in-depth analysis, with the trend of impulses from statistically significant variables—having observed the important roles played by hc, sc, and particularly iq, as well as the control variables GDP per capita and population density—in increasing the percentage of waste sorting. This impulse analysis suggests for policy interventions that there would be immediate effects (1–2 years) due to the improvement of our intangible capitals, but also a short duration. This suggests the need for lasting and structural interventions.