When we’re very young, a best friend can be someone you met two hours ago in the sandbox.

As we get older, we tend to get more discerning about the company we keep, and opportunities to meet new people become more complex and less frequent.

This change is thrown into sharp relief when you move to a new state or distant city as an adult and leave behind tight-knit friendships. How do you find kindred souls in a new location?

Parents of small children often find it easier to build a new network of friends because playgrounds, Little League games and Scouts trips are natural places for adults to make acquaintances who can blossom into friends. For the rest of us, rebuilding a cadre of friends might need a little more strategizing.

And there are so many reasons to move these days that it’d be a shame to let fear of being friendless stop you.

First of all, as soon as you learn you may move, ask your family and friends if they know someone — anyone — who already lives in what will soon be your new home. Disregard their age, marital status, politics, favorite TV program or anything else that might not suit your taste.

You want to ask this person to give you the lay of the land, recommend neighborhoods to live in and those to avoid, local events you should attend and things you should avoid, and ideally they will offer to introduce you to others, jump-starting the reconstruction of your social life.

Reach out to your new “friend guide” a day or two after you arrive in the new city. Ask to meet for coffee on a date convenient to them, be sure to arrive early and — don’t forget — pick up the check. You might get lucky and effortlessly fall into a new social circle.

“Adults have this myth that other adults already have all the friends they want,” says the psychologist Irene S. Levine, who wrote the book “Best Friends Forever” and blogs at thefriendshipblog.com.

But if not, turn to the world of apps. Some are specifically aimed at kindling friendships.

Peanut is a social networking app that says it’s “where mamas meet;” some users describe it as a platonic “Tinder for Moms.” Bumble, a dating app, is rolling out Bumble BFF, an app for arranging dates with your new best friend forever.

Meetup.com is a well-known site that offers users countless options to meet new people, from hiking to book groups to meditation. If you don’t find an activity you’re interested in, you can start your own group.

Business networking apps such as Shapr and LinkedIn are being asked to work overtime to help their users locate potential friends. The apps harvest their users’ age, location, title and industry and run that information through an algorithm to find professionals with matching interests and similar professional goals.

LinkedIn’s People You May Know service looks at the number of people users have in common, if they work at the same company or in the same industry, or if they attended the same university. Shapr’s algorithm goes a step further and curates a daily batch of 10 to 20 profiles of active users who share similar interests and goals.

Clubs, concerts and other cultural events have long been promising places to meet new friends, and they remain so today. Apps such as Eventbrite, Nearify and Radiate make it easier to get a comprehensive list of which artists are in town, where they will perform and sometimes which people from your small-but (hopefully) growing social circle plan to go.

While apps can save time in your search for friends in an unfamiliar place, they are not the only tools to consider.

Conventional networking — casual meetings with your new coworkers, friends of friends and former classmates — can still aid in expanding your roster of friends. But Columbia University professors in 2007 published research concluding that business “mixers” — unstructured social events meant to encourage networking — were ineffective. Attendees tended to socialize with people they knew beforehand or people of the same age, race, gender, etc.

Volunteering can be a way to meet people with similar interests, whether that involves carpentry at Habitat for Humanity, finding homes for rescue dogs or working at a food bank. And even if you don’t make a new friend, you’ve done some good.

Book clubs are a good way to meet friends, especially if you can find one specializing in a particular genre, author, topic or time period you like. Sometimes local bookstores or libraries run book clubs, so it’s worth starting there.

Even better: adopt a dog. Over the years, at least four scientific studies in the United States and abroad have demonstrated that people are much more likely to approach a stranger walking or playing with a dog than a stranger alone.

In a survey commissioned by the American Kennel Club, the data showed 58% of men said bringing a puppy to a park is a very effective means to meet women. And 46% of women surveyed said they’d stop and talk to anyone with a cute puppy.

“Dogs act as social ‘ice breakers’ and help people strike up friendly conversation with others,” Dr. June McNicholas from the University of Warwick in the United Kingdom told Policy Genius magazine.

“It is difficult for us to strike up a conversation with a complete stranger — all sorts of ulterior motives may be suspected. But being with a dog (or other pet) gives a safe, non-threatening, neutral topic to start a conversation.”