Child psychiatrists have little experience in diagnosing bipolarity. Studies have shown that it takes them an average of about ten years after the initial appearance of the relevant symptoms to arrive at a correct diagnosis. A second set of problems has to do with the still unresolved controversies regarding the nature of the continuum, if any, linking the clinical entities that are manifested in childhood, adolescence, and adulthood. In the case of children, for example, comorbidity involving attention disorders with or without hyperactivity (ADHD) can be expected to occur with frequency. Nevertheless, the clinical symptomology of ADHD, and especially of attention deficits is not familiar to psychiatrists who work with adults. The above reflections suggest the need for studies focusing on the developmental evolution of the relevant semiology, especially since little work has been done to bring together specialists in child and adult psychiatry for this purpose. The present article attempts to fill this need. It also seeks to redress the imbalance due to the fact that most previous studies have been designed solely on the basis of a semiology by category that assembles a set of criteria deemed necessary to obtain a diagnosis and that approaches the clinical symptomology in light of semiological presuppositions that are thought to be identical and are expected to hold in all cases. This article therefore offers a panoramic and detailed presentation of a dimensional and developmental semiology of ADHD and bipolarity. The goal of the study presented herein is to identify the clinical symptomologies of bipolarity and ADHD with more precision, from early childhood on through adulthood and to refine the relevant differential diagnosis by means of a simultaneous analysis of these two clinical phenomena. The method used in this study is a qualitative one involving the following two steps: first, it examined the relevant phenomena and clinical anamnesis in order to discover the greatest possible number of semiological micro-signs, with the goal of establishing a dimensional semiology v. Second, it included subjects of different ages in order to identify a v developmental semiology v. With this intention, we observed 170 children and 55 adults with bipolar symptoms and 14 children and 7 adults with ADHD (both sets of subjects had no other comorbidity), attempting to look each time as freshly as possible, without limiting ourselves to the criteria typical of diagnosis by category. For ADHD, this study introduces new semiological concepts. These concepts revolve around three distinctions: between (1) a preponderance of divergent attention and a preponderance of convergent attention; between (2) the semiology of pre-attentional difficulties (relating to ambient noise and excessive information flow) and the semiology of attention disorders per se; between (3) simple impulsiveness and an impulsiveness related to disruptive behavior. As a third step, we present the developmental evolution of the relevant clinical phenomena. For bipolarity, the study highlights a simple manic bipolar temperament comprising seven semiological axes: 1/a "super-energetic" form; 2/ sleep disorders; 3/ an "uneasiness in the situation of being alone"; 4/ "expressive emotional colors"; 5/ excitability, disinhibition, and cravings; 6/ a preponderance of divergent attention over convergent attention; 7/ the tendency toward hyperactivity. The description of the clinical symptomology of "uneasiness in the situation of being alone" - which is the most original aspect of this research reflects an incapacity to remain alone with oneself in a calm manner. This discomfort is to be distinguished from separation anxiety, though there can be a continuum between the two; it is not a pathognomonic symptom of bipolarity, yet it does seem to be systematically present as a part of it. After having treated bipolarity, we go on to lay out the criteria for the differential diagnosis between simple manic bipolar temperament" and ADHD. At this point, we propose an original classification of bipolar disorders in childhood, made up of three semiological sub-groups of bipolar states, to which we add a fourth semiological group for unipolar depressions. Various comorbidities can enter the scene and modify the basic clinical picture. Lastly, we sketch a differential diagnosis with respect to schizoaffective disorder. In discussing the results presented here, we suggest the possibility of a new "dimensional and developmental nosology". At the time of this writing, a further stage of the research outlined in this article is underway with the aim of establishing a quantitative analysis of the semiology outlined above.