<b><i>Background/Aims:</i></b> Progress in the development of DSM/ICD taxonomies has revealed limitations of both label-based and dimensionality approaches. These approaches fail to address the contingent, nonlinear, context-dependent, and transient nature of those biomarkers linked to specific symptoms of psychopathology or to specific biobehavioural traits of healthy people (temperament). The present review aims to highlight the benefits of a functional constructivism approach in the analysis of neurochemical biomarkers underlying temperament and psychopathology. <b><i>Method:</i></b> A review was performed. <b><i>Results:</i></b> Eight systems are identified, and 7 neurochemical ensembles are described in detail. None of these systems is represented by a single neurotransmitter; all of them work in ensembles with each other. The functionality and relationships of these systems are presented here in association with their roles in action construction, with brief examples of psychopathology. The review introduces formal symbols for these systems to facilitate their more compact analysis in the future. <b><i>Conclusion:</i></b> This analysis demonstrates the possibility of constructivism-based unifying taxonomies of temperament (in the framework of the neurochemical model functional ensemble of temperament) and classifications of psychiatric disorders. Such taxonomies would present the biobehavioural individual differences as consistent behavioural patterns generated within a formally structured space of parameters related to the generation of behaviour.