Compared to the literature on quantitative and statistical modelling, there is a lack of research on qualitative environmental-related modelling, which focuses on a conceptual-theory-based model. Therefore, this paper attempts to formulate a qualitative institutional-social-ecological model, by showcasing how the 10 steps modelling is relevant and is applied to the institutional-property-rights model of neighbourhood residential commons. Using an instance from one case study (i.e., Sabah, Malaysia), a conceptual problem-solution model describing local property-rights system tragedies of public open space (POS) governance and quality, and the emergence of self-governing collective action was demonstrated. Methodologically, the modelling procedures were specified as a 10-step process, starting with setting the objectives of the model and concluding with the validation of suitability and usefulness of the model. The validation was conducted using the experts' opinion, via the semi-structured interviews with five public officials. With slight necessary amendments, the model was proven practical, useful, flexible, reliable and valid in serving its purposes in understanding and predicting the effects of local property-rights system tragedies on POS commons dilemmas, and the subsequent emergence and necessity of a self-governing solution. This local model provides policy insights to the local public officials, which facilitate their institutional-social-ecological decision-making process that helps improve local POS governance and quality.Resources 2018, 7, 62 2 of 23 framework for qualitative environmental-related modelling has been less paid attention to. Against this background, this study focuses more on qualitative social-ecological system modelling. That is this local model nested few supplemental quantitative/statistical approaches within it; thus, as a whole, the model design is still called qualitative (see Forbus [4] on the qualitative mathematics, which is considered as qualitative modelling). This paper employs notable Jakeman's et al. [3] model development and validation steps. This is because Jakeman et al. [3] outlined clear ten steps modelling to explain and support resource management and use system, which is deemed relevant to this study's social-ecological governance dimension. More essentially, although this 10-step modelling is originally and primarily crafted for quantitative modelling, it can also be sufficiently generic and inclusive for qualitative modelling [5,6] and is applicable in environmental and economic related fields. See Jorgensen and Bendoricchio's [7] and Wainwright and Mulligan's [8] ecological and environmental modelling, and Grafton et al. [9] for economic-environmental systems. Based on our literature search, the application of the ten steps in qualitative-designed modelling is indeed very limited; therefore, such attempt is worth to be explored in this study so that it may methodologically value-add to the 10-step modelling framework, regarding its application validity and flexi...