When I was in my first graduate school many years ago one of my favorite professors made what seemed to many of us to be an astonishing comment. I have since realize how right he was. What he said was this: "Adolescence begins at puberty and ends when the person resolves their identity." That is, adolescence begins when puberty begins and ends when a person figures out who they are and who they are not. I remember many of us in that class raised our hands and said, "What that means is that there are 40, 50, 60 and 70 year old adolescents running all over the place!" To which the professor replied, "Yes. Lock that thought down. If you keep it in mind you will be more successful in working with people."
Adolescence is a period that includes cognitive, physical, and emotional change. It is a period of discovery and identity formation. New roles are explored. Voices change, sexual organs develop, hormones flow, adult-like personality patterns begin to emerge, and new patterns of relationship formation are tried out. Individuals become more concerned with whether they are liked by others. Activities are often now in groups. People pair up. Texting is common. Drama begins to be a part of relationships. Misunderstandings of intent or action are common. Comparisons are being made more often. Self-examination (especially physical) is now important. Adolescents want to be part of the group, but not too much part of the group. They want to be seen as individuals, but not too much as individuals. Calibrating who I am and where I fit is taking place. Peers are much more important than parents.
My larger point in all of this is to note that it is more than possible to be a 20 to 90 year old and still be an adolescent. That you have cars, houses, boats, and children (or grandchildren) does not mean you are an adult. Adolescents are into themselves and are trying to figure out who they are. It's quite possible to get to your late teens or early twenties and not have a clue about who you are or any sense of personal identity. In fact, I see lots of people in my clinical practice who spend time with lots of other people, and all of them are pretending to be adults but don't really know what they are doing other than maintaining the mass pretense that they are adults. It's a fiction.
An adult is someone who can function independently and has good boundaries. It is someone who understands, appreciates and supports the concept of limits. An adult understands that freedom itself exists within a limit. This person is responsible, self-confident, assertive (expects the possibility of 'no' when expressing a need), and is not manipulative (passive-aggressive).
So I ask my patients to give me a definition of 'maturity.' What does it mean to be mature? This is important because once we have an idea of what it means to be a mature human being, we can use that definition to guide our behavior. In addition, we can use that definition to build strength into others by referencing maturity in discipline, goals, outcomes, and process. Any definition of maturity is bound to be incomplete but the process of definition is incredibly valuable.
My working definition of maturity
A dedication to reality -- live with what is, not what is supposed to be. The capacity to delay gratification -- do your 'homework' first, and play afterwards. To be responsible TO people but not FOR people -- avoid co-dependencies. Speak the truth with love -- if one is only truthful, it is often brutal; if one is only loving, it is often fluffy and light and without reality. Fix the problem, not the blame -- similar to a dedication to reality, this principle helps keep our energy positive and forward looking. Being right is over-rated -- the reality is that emotion is the car, intellect is a passenger; if I don't trust you, it doesn't matter what you say, I won't follow. Have as few secrets as possible -- the presence of a secret is more damaging than the content; secrets create false alliances and inhibit conversation on ANY topic. Be assertive -- this means sharing what you want and allowing the other to say NO; if they can't potentially say 'no' then you cannot trust their 'yes' Do not be passive-aggressive -- we see this when we are being manipulated; the manipulator will never know if what they have is by choice or coercion Act justly, love mercy, walk humbly -- best not to take yourself too seriously