Adolescence is one of the most complex and layered developmental periods in life, which current research situates between the ages of ten and nineteen years old (e.g., [1]) and is characterized by profound and rapid changes in biological, cognitive, emotional, and relational areas [2]. This phase is not a homogeneous period, as the kind of developmental trajectories can vary according to individual characteristics and environmental influences ^[3][4][3,4]. Thus, according to a positive view of individual development and socio-cognitive approaches (e.g., [5]), individuals, as adolescents, do not passively change in their lives; instead, they can actively model and influence them, contributing to restructuring identity and socio-relational aspects in response to environmental and situational demands [6]. The way through which these transactions happen, and the valence of individual developmental pathways, can affect concurrent and longitudinal well-being and adjustment ^[1][6][1,6].

At a descriptive level, research on adolescence evidenced the presence of several specific stages through which adolescence can be divided, such as puberty (9–10 years old), early adolescence (11–13 years old), middle adolescence (14–17 years old), and late adolescence (17–19 years old), and each of them is characterized by specific transactions in terms of relational, emotional, and cognitive development [2]. During these stages, youths undergo a profound cerebral reorganization, particularly in the prefrontal and limbic areas, which modulate decision-making abilities, self-regulation, emotional regulation, and social functioning ^[7][8][7,8]. In particular, the first stage is characterized especially by changes in emotional-cognitive domain, and in biological transformation; during early adolescence, temperamental bases for emotionality started to stabilize; during middle adolescence, changes in self-regulation and social functioning are predominant; while during late adolescence all the changes and modifications of the previous stages have to integrate in a stable and unified trajectory ^[2][3][8][2,3,8].

At the neurobiological level, adolescence is characterized by a significant reorganization of the Central Nervous System, which leads to the maturation of the prefrontal cortex—the hub of executive functions—and occurs at a slower rate than the limbic system—the hub of emotionality and emotion regulation [9]. During puberty, there is a significant activation of the HPG system (i.e., Hypothalamic–Pituitary–Gonadal system), leading to an increase in the production of sexual hormones that influence behavioral and physical changes [10]. Recent studies have demonstrated that cerebral maturation follows a distinct pathway from psycho-physical development, as the impulsivity and reward sensitivity systems are activated earlier, while the cognitive control system, related to the prefrontal cortex, fully develops during late adolescence and early adulthood [11]. This temporary imbalance leads to an increase in impulsivity, emotional vulnerability, and sensitivity to environmental cues, especially among those who receive emotional and relational information (e.g., [8]). As such, emotional and self-regulation development are closely connected to this neurological reorganization, which influences not only temperamental characteristics but also more fine-grained abilities, such as decision-making, risk-taking, perceptual sensitivity, and social-information processing [11].

Contextually, youth develop more complex and novel cognitive strategies, as thoughts become more abstract and reflective, although these aspects do not always align with emotional developmental pathways, serving as a further imbalance factor ^[8][12][8,12]. Self-awareness, as well as awareness of personal identity conflicts and dissonances between the Self and the environment, can influence these cognitive processes, leading adolescents to develop internal tensions due to a lack of self-regulation and integration abilities ^[6][12][6,12]. At the identity level, during adolescence, there is a consolidation of future adult identity formation [13]. Abilities such as autonomy, development of a stable self-image, empathy, and emotional and affective regulation are crucial, and they are influenced by individual differences and significant socio-relational contexts, including family, school, and peer contexts ^[13][14][13,14].

At a psychological level, youths are engaged in a crucial process of exploration and identity consolidation, which involves the reorganization of their relational behaviors with family and peer relations ^[14][15][14,15]. The relational reorganization is interlinked with the development of autonomy-granting and perspective-taking [7]. The social dimension becomes crucial because peer groups serve as a reference for self-evaluation and behavioral experimentation, significantly influencing individual choices and behaviors, especially in risky situations (e.g., [16]). Emotional functioning is another crucial aspect, as it can significantly influence decision-making [11]. In addition, peers may serve as a vehicle for emotion regulation, and the presence of peers may influence the tendency to engage in both pleasing and risky experiences, thereby inhibiting the evaluation of consequences ^[17][18][17,18].

Thus, individual differences play a fundamental role in adolescent changes and transformation over time, especially those related to personality and temperamental characteristics (e.g., ^[3][19][3,19]). Temperamental dimensions, observable from the very beginning of life, reflect neurobiological dispositions that are predominantly stable during infancy and childhood, helping children regulate their responses to environmental stimulation ^[20][21][20,21]. On the other hand, personality is a more complex construct that develops from the interaction between temperamental dispositions and relational or experiential situations, and progressively expands over the life course [3]. Research has firmly demonstrated that temperamental characteristics, such as effortful control (i.e., the voluntary self-regulatory abilities), emotional reactivity, and individual orientation toward social approach, play a fundamental role in psychological well-being, also affecting the quality of interpersonal relationships and academic achievement (e.g., ^[3][22][23][3,22,23]). In this sense, temperament and personality can act as protective or vulnerability factors, depending on the context and individual differences encountered in dealing with specific situations ^[3][23][3,23].

Therefore, the study of individual differences throughout adolescence is not only a theoretical issue, but also a practical need, as a vehicle to promote more effective clinical, preventive, and educational programs ^[23][24][23,24]. Moving research strengths in this direction, individual differences may serve as a starting point to enhance and sustain individual development from childhood through adulthood ^[1][2][19][1,2,19]. These strengths may facilitate considering adolescence as a phase of plasticity, not only a vulnerable developmental period, in which adopting a systemic and integrated approach is crucial to sustain individual potentiality and specific life contexts ^[2][11][2,11]. In this view, the promotion of socio-emotional competences in adolescents is the key, supporting the idea that adolescence may serve as a “window of opportunities” for individuals, in which clinicians and researchers may operate to prevent the development of maladaptive pathways over time ^[1][25][1,25].

The person-oriented approach represents a crucial turning point in personality and developmental research, as this view focuses not on single traits, but on configurations of characteristics over the life course [26]. Unlike variable-centered methods, which analyze each dimension separately, person-oriented methods identify patterns of psychological profiles, emphasizing the complexity of trait interactions and their manifestation [27]. During adolescence, this perspective enables the examination of individual pattern development, offering more specific information on the likelihood of experiencing maladjustment (e.g., ^[28][29][28,29]). Starting from the pioneering works by Block and Block [30], in developmental studies, research identified three main patterns (e.g., ^[31][32][31,32]):

(a)

An adjusted pattern, characterized by high self-regulation, low negative emotionality, adequate extraversion and activity levels, and optimal affiliation toward others.

(b)

An overcontrolled pattern, characterized by a tendency for inhibition and social withdrawal, very high controlling levels, and relationships and emotional issues, which is mainly associated with internalizing problems, such as anxiety, panic disorders, depressive symptoms, and isolation.

(c)

An undercontrolled pattern, characterized by significant issues in self-regulation, high reactivity and motor activation, attention deficit, and negative reactive emotions, associated with impulsive and potentially risky behavioral responses, which mainly manifest externalizing problems, such as aggressive or antisocial conduct, excessive or addictive behaviors, disruptive behaviors, and academic maladjustment.

These patterns are especially sensitive to individual experiences and environmental influences, and their early identification may serve as a starting point for implementing tailored preventive interventions that can support individual resources in containing and monitoring vulnerabilities ^[28][32][33][28,32,33].

The study of individual differences using this lens represents a fundamental aspect for adequately understanding the variety of feasible individual pathways and distinguishing between adaptive and maladaptive trajectories ^[19][28][32][19,28,32]. Adolescents are navigating the interplay between their predispositions and environmental influences, including family, school, and peers, that shape their development [3]. The identification of personality patterns enables researchers to describe individual differences in developmental trajectories, design tailored educational, preventive, or promotive interventions, and support youths’ resilience and the expression of their potential ^[19][23][34][19,23,34]. The integration of a person-centered approach with a lifespan perspective can provide significant tools for observing, understanding, and supporting adolescents, thereby enhancing the uniqueness of individual trajectories ^{[11][19][23][35]}[11,19,23,35].