Summer came bounding in with Pilobolus in Page Auditorium as the American Dance Festival continued its happy tradition of presenting this well-loved company annually. The hall was full and the atmosphere festive for the first of its four performances.* The program included three works from 2007 and an early solo from 1973, culminating with 2004’s super-charged “Megawatt.”

Part of the 36-year-old troupe’s charm is that it never grows up. No matter how sophisticated or emotional the dances are, they remain playful — and to do what they do, the dancers must be in the youthful physical prime of life. There’s an essential youngness to Pilobolus that is refreshing, energizing and as easy to love as a roomful of happy five-year-olds. Who wouldn’t want to watch flexible, powerful, sculpted young bodies in Lycra cavorting through amazing antics of motion and structural engineering? It’s a thrilling spectacle.

As if in a nod to this idea, the program opened with the sextet “B’zyrk,” with its vivid images of circus performers and their audience — a kind of company self-portrait, perhaps, in dance. Itinerant entertainers have traveled the world time out of mind, and this bold, cheerfully self-aware piece celebrates the small circus with its physical feats, visual humor, and little tricks. Pilobolus, given to broad jokes and inspired silliness concocted by a small, highly interdependent and collaborative group, could be compared to the small circus of past centuries. (Some people would say that a nearer reference, especially in a piece like “B’zyrk,” would be early Monty Python. Certainly there were moments when John Cleese seemed to be on stage, but he too is part of the line, stretching back forever, of artist-entertainers who take their spectacles to the people.) “B’zyrk,” full of oversize characters carrying on, is warm-hearted and funny as well as looking great.

Pilobolus’ dancers are aided inestimably in their spectacle-making by their lighting designers, without whose carefully planned effects of color, shadow, and highlight the dances would lose a great deal of their impact. Would the delightful “Pseudopodia,” performed here by Jun Kuribayashi to audience cheers as well as its all-percussion score, be quite so delightful if the stage and dancer weren’t saturated with colored light? The company uses light very effectively to create a stage world where the highly unusual is the norm — a place of strange and wonderful changes and transformations.

Transformation, metamorphosis and the flow of change through time are some of Pilobolus’ deep themes. They interlock these concerns with their on-going investigations into stability and structure, and the dynamic tension created is in full evidence in the mesmerizing “Rushes,” which received its world premiere on the 21st. Pilobolus’ dances are always the result of collaboration, usually by one or more the group’s three artistic directors and the dancers. For “Rushes,” however, the company collaborated with Israeli choreographers Inbal Pinto and Avshalom Pollak, bringing in a different energy. It’s obviously Pilobolus, but there are sharper edges and darker shadows. It uses props — pale wooden straight chairs and a suitcase — and at times is like a through-the-looking-glass game of musical chairs. At other times, the chairs (like the dancers) morph: at one point they form an angular exoskeleton for the interior dancer. Searing images are created by paired or multiple dancers, punctuated by whipping lines of motion fringed with spiny chairs. All this goes on to a surprising combination of music by Eddie Sauter, Miles Davis, John Blow, the Dukes of Dixieland, and Arvo Pärt. And then there’s the bent man in the tail coat, walking on tiptoe, and always carrying that boxy leather suitcase. I think that suitcase must be full of spells and charms.

“Rushes” and the untitled duet that opened the second half were the highlights of the program. The duet, danced by Annika Sheaff and North Carolina native Manelich Minniefee, was a beautiful little dance of love built on equality, trust, and generosity, made doubly luminous by the physical beauty and grace of the performers. Its bijou quality was further enhanced by its proximity to the rousing closing dance.

Starting wide open and going on from there, to the music of Primus, Radiohead and Squarepusher, “Megawatt” makes a fine finale. Pilobolus doesn’t do sarcasm, but they do delve into irony. In “Megawatt” they convey the fully-wired, high-energy-usage, frenetic state of our world through the profligate expenditure of their own energies on all the glorious astonishing moves that continue to make them so admired. Fortunately, Pilobolus seems to be a renewable energy resource.

*Pilobolus continues through June 23. See our calendar for details.