As party planning guides go, this one rivals any you’ll find for organizing a major social event: Its 94-page book includes menu ideas, decorating tips, thoughts on creating the perfect gift bag. There are suggestions for spa treatments your guests can enjoy, and the kit comes packaged in a shiny box with invitations, matching envelopes and a guest book.

But this party kit isn’t designed for someone planning a wedding or bar mitzvah. It’s for children who want to invite a few friends to sleep over.

“Little MissMatched’s Pajama Party in a Box” packages a childhood experience in a neat, organized, already-thought-out-for-you box. The enclosed book suggests adding your own ideas. But the kit’s very existence brings to sleepovers a level of structure that was unheard of a generation ago.

Plenty of other boxed sets have similar goals. Kids once fueled their imaginations by playing dress-up with old clothes, exploring their parents’ history (and closets) while draping themselves in the garb of adulthood. Today’s parents can avoid the trouble of a messy closet or a child stumbling around in oversized shoes by buying a prepacked trunk of dress-up clothes sized for kids.

The popularity of boxed sets for kids isn’t surprising in a land that loves its Starbucks and McDonald’s and dozens of other predictable experiences, says Texas Christian University sociology professor Keith Whitworth.

Buying a boxed set for playing dress up “eliminates the human variables to a degree and provides a comfortable response upon purchase.”

These sets often boast pretty packaging, catchy names and the promise of extra-fabulous fun. But when we package childhood pursuits that once unfolded organically, is anything lost?

As with most of the trappings of modern parenthood, how you choose to use a boxed set can make a big difference in what your kids get out of it. Some things parents should know:

• Children need to add their own elements.

Children’s lives are more structured than ever, says Wendy S. Grolnick, a child development researcher and professor at Clark University in Worcester, Mass. Boxed sets, says Grolnick, can “take some of the creativity and spontaneity out of these experiences, and give a sense that there’s a best way to do it or a right way to do it.”

Let kids know they can add to the experience as they wish.

Parents buy boxed sets because “their desire is to have it be really good. But it’ll be really good to your child if they come up with it themselves,” Grolnick says.

Sally Lee, editor-in-chief of Parents magazine, points out that kids almost always have their own way of doing things.

“I don’t think they’re slavishly going to follow prescribed ideas of what a pajama party should be like. … Very few people ever follow the instructions anyway,” she says.

• Parents need to stay involved.

Organized packages can be a great time-saver for very busy parents, Lee says.

“I found last year at Target all these outdoor games together: a badminton set, tennis, rings, all for like $19.99. I was so grateful it was all put together and we could choose what we wanted to play,” she says.

The time saved can be spent together.

But Lee advises parents to check their motives: “If you’re buying a package and saying to your child, ‘Get on with it,’ and not investing yourself in that playtime, then that’s a problem.”

• Give your kids space – not just stuff.

Lee says all kids, those with the hottest “it” toy and those without need time and freedom.

“I don’t think these packages can do any damage,” especially if kids have plenty of time for free play. “That’s where the bigger threat is, the lack of resilience and not being able to play alone and not being able to lie back and watch the clouds float by,” Lee says.