Astrocytes play a crucial role in regulating synaptic and vascular compartments in the brain through various released factors and membrane-bound proteins. Imbalanced astrocyte activity can negatively impact brain development, leading to severe pathologies. Clinical and pre-clinical studies show alterations in astrocyte cell number, morphology, molecular makeup, and astrocyte-dependent processes in different brain regions in neurodevelopmental (ND) and neuropsychiatric (NP) disorders. Astrocytes proliferate, differentiate, and mature during the critical period of early postnatal brain development, a time window of elevated glia-dependent regulation of synapse formation/elimination, which is pivotal in refining synaptic connectivity. Any intrinsic or extrinsic factors altering these processes during the critical period may result in aberrant synaptic remodeling and the onset of mental disorders. Astrocytes, due to their bridging position between synaptic and vascular compartments, can "compute" the brain state and secrete factors in the bloodstream, which may serve as diagnostic biomarkers of distinct healthy or disease conditions. Recent advancements regarding astrogenesis and astrocyte-mediated regulation of neuronal network remodeling during early postnatal critical periods, focusing on synapse elimination, are discussed. Alternative hypotheses for the involvement of aberrancies in these processes in the onset of ND and NP disorders are proposed. Considering the differential prevalence of certain brain disorders between males and females, putative sex-dependent influences on these neurodevelopmental events are also discussed. Understanding age- and sex-dependent astrocyte-specific molecular and functional changes may help identify biomarkers of distinct cellular (dys)functions in health and disease, favoring the development of diagnostic tools or tailored treatment options for male/female patients. Astrocytes are the most abundant subtype of glial cells in the brain and spinal cord. They have a star-shaped morphology with few major processes extending from the soma, which ramify into numerous fine branches and leaflets at more distal locations. During embryogenesis, astrocytes are generated from radial glia (RG), which self-renew and differentiate into neurons and macroglia cells, such as astrocytes, oligodendrocytes, and Schwann cells. Cell divisions of RGs are predominantly neurogenic at early/mid-gestation and turn into gliogenic at late-gestation/early postnatal developmental stages. The initial steps of gliogenesis produce astrocyte precursors, which then proliferate in different brain areas to increase their numbers and give rise to mature astrocytes. Several studies highlight the heterogeneity of astrocyte morphologies and functions in various regions of the central nervous system (CNS). The most specialized subtypes display very distinctive structural and functional properties. In addition to these general features, hominid primates exhibit evolutionary unique subtypes of astrocytes. Astrocytes show a great range of heterogeneity in the acquisition of various competencies selectively matching the function(s) of neighboring cells. To gain such a highAstrocytes play a crucial role in regulating synaptic and vascular compartments in the brain through various released factors and membrane-bound proteins. Imbalanced astrocyte activity can negatively impact brain development, leading to severe pathologies. Clinical and pre-clinical studies show alterations in astrocyte cell number, morphology, molecular makeup, and astrocyte-dependent processes in different brain regions in neurodevelopmental (ND) and neuropsychiatric (NP) disorders. Astrocytes proliferate, differentiate, and mature during the critical period of early postnatal brain development, a time window of elevated glia-dependent regulation of synapse formation/elimination, which is pivotal in refining synaptic connectivity. Any intrinsic or extrinsic factors altering these processes during the critical period may result in aberrant synaptic remodeling and the onset of mental disorders. Astrocytes, due to their bridging position between synaptic and vascular compartments, can "compute" the brain state and secrete factors in the bloodstream, which may serve as diagnostic biomarkers of distinct healthy or disease conditions. Recent advancements regarding astrogenesis and astrocyte-mediated regulation of neuronal network remodeling during early postnatal critical periods, focusing on synapse elimination, are discussed. Alternative hypotheses for the involvement of aberrancies in these processes in the onset of ND and NP disorders are proposed. Considering the differential prevalence of certain brain disorders between males and females, putative sex-dependent influences on these neurodevelopmental events are also discussed. Understanding age- and sex-dependent astrocyte-specific molecular and functional changes may help identify biomarkers of distinct cellular (dys)functions in health and disease, favoring the development of diagnostic tools or tailored treatment options for male/female patients. Astrocytes are the most abundant subtype of glial cells in the brain and spinal cord. They have a star-shaped morphology with few major processes extending from the soma, which ramify into numerous fine branches and leaflets at more distal locations. During embryogenesis, astrocytes are generated from radial glia (RG), which self-renew and differentiate into neurons and macroglia cells, such as astrocytes, oligodendrocytes, and Schwann cells. Cell divisions of RGs are predominantly neurogenic at early/mid-gestation and turn into gliogenic at late-gestation/early postnatal developmental stages. The initial steps of gliogenesis produce astrocyte precursors, which then proliferate in different brain areas to increase their numbers and give rise to mature astrocytes. Several studies highlight the heterogeneity of astrocyte morphologies and functions in various regions of the central nervous system (CNS). The most specialized subtypes display very distinctive structural and functional properties. In addition to these general features, hominid primates exhibit evolutionary unique subtypes of astrocytes. Astrocytes show a great range of heterogeneity in the acquisition of various competencies selectively matching the function(s) of neighboring cells. To gain such a high