"Separation anxiety" gets used two different ways — an ordinary stage almost every preschooler passes through, and a clinical diagnosis for a much smaller group — and knowing which one you are dealing with changes what actually helps.
Most young children go through a stretch where separating from a parent brings real distress; that is developmental, not a disorder, and most preschoolers move through it. A smaller number of children experience anxiety that is severe, does not ease with a predictable routine, and interferes with sleep, school, or friendships — that is a clinical picture, and it needs a professional, not a printable.
Anxiety feeds on not knowing what happens next. A visual schedule of the day, a warning well before a new separation — "Grandma is picking you up today, not me" — and a goodbye that never changes shape all reduce the number of unknowns your preschooler is holding at once.
Warm, specific, and short, in the same order every time: name what is happening, name who is coming back and when, one hug, go. The ritual only works if it survives a bad morning — the day you are running late is exactly the day to keep it, not shorten it further or skip it.
A small object from home does more when it has a specific task attached to it, rather than being a general-purpose comfort item: "hold this until snack time, then it goes in your bag." A job gives the object an endpoint, which mirrors the thing the anxiety is actually about — not knowing when the separation ends.
If the anxiety is not easing after a sustained period of a consistent routine, if it is spreading into settings that are not about separation at all, or if it comes with physical complaints, sleep loss, or refusal to attend school, raise it directly with your pediatrician or your preschooler's support staff. This page can describe what is ordinary; it cannot diagnose your child.
Both, depending on severity. Most preschoolers experience a phase of it and grow out of it with a predictable routine. A smaller number have a diagnosable anxiety disorder that needs professional support — the difference is severity and how much it interferes with daily life, which a pediatrician assesses, not a search.
There is no single number worth quoting here; it is commonly discussed as most intense in the toddler and early preschool years and easing as children build up experience with separations that reliably end well. Individual children vary a great deal.
Often the latter. A new, sustained separation is frequently the first time the anxiety becomes visible, rather than something the new setting created out of nothing.
Part of our guide to Starting daycare.