The following is a suggested group full moon ritual for use with the the Celtic Tree Calendar. This format has worked well for me, but please feel free to modify it as desired. 'An it harm none, do as ye will.

Purification of circle:

Pass an incense mixture of frankincense, myrhh and dragon's blood resin clockwise (deosil) around the circle. Smudge each member as it passes. This represents the elements of air and fire.

Pass a chalice of salt water around the circle. Sprinkle the ground and allow each member to annoint her/himself as the chalice passes. This represents the elements of water and earth.

Casting the circle:

Starting in the east, walk once around clockwise (deosil) while pointing either your athame, wand or forefinger at the perimiter of the circle. Visualize blue flames springing forth and taking form as shimmering blue energy at the perimiter, eventually taking the form of a sphere. Say the following while walking:

"This circle I cast by full moon light,
A sacred space to perform this rite,
With air, fire, water and earth to bless,
Until we withdraw their powers hence.
A sphere of light around us grows,
And as above, then so below.
Now 'thrice we have called, that all may see,
This circle is cast, so mote it be."

Quarter Calls:

Hail to the Watchtower of the East!
I call upon the dragon Sairys, ruler of winds and clouds, to guard and protect this circle.
I summon the powers of air,
Clear sighted eagle,
Golden dawn of new beginnings,
Refreshing winds of change.
Come to our circle, dazzling and brilliant, to aid us in our rite.
Be here now.

Hail to the Watchtower of the South!
I call upon the dragon Fafnir, ruler of sumbeams and flames, to guard and protect this circle.
I summon the powers of fire,
Courageous lion,
Passion of the red noon,
Warm glow of the hearth.
Come to our circle, fiery and blazing, to aid us in our rite.
Be here now.

Hail to the Watchtower of the West!
I call upon the dragon Naelyan, ruler of seas and lakes, to guard and protect this circle.
I summon the powers of water,
Ancient serpent of wisdom,
Soothing azure dusk,
Sparkling fountain and shimmering pool.
Come to our circle, gentle and buoyant, to aid us in our rite.
Be here now.

Hail to the Watchtower of the North!
I call upon the dragon Grael, ruler of mountains and lands, to guard and protect this circle.
I summon the powers of earth,
Mighty bull of fertile fields,
Silent repose of black midnight,
Deep cave of wisdom and knowledge.
Come to our circle, solid and strong, to aid us in our rite.
Be here now.

Invocation to the Goddess:

"Wondrous Lady of the Moon
Mistress of all magick and protectress of all
Life-giving mother
We greet you at the height of the moon's power
We invite you to attend our Full Moon rite"

Group chant:
"The Goddess is alive
and magick is afoot"

Recite or read aloud "The Charge of the Goddess".

Invocation to the God:

"Radiant King of the Heavens
Master of beasts wild and free
Horned stag
We greet you at the height of the moon's power
We invite you to attend our Full Moon rite"

Group chant:
"Seed sower, grain reborn
Horned one come."

Statement of Purpose:

Discuss the attributes of the tree that is represented by the month celebrated on the Celtic Tree Calendar.

Working:

Pass a chalice of wine around the circle. Each participant discusses to what end s/he would like to use the energy that will be raised. Ideally the goal will be in line with the attributes of the tree moon. Each participant visualizes putting her/his goal into the wine, hence mixing the group's goals together into a whole.

Power can be raised by chanting, drumming, dancing, or any combination thereof. The following is one of my favorite full moon chants:

"Powerful moon of radiant light
Weave us a web that spins the night
Web of stars that holds the dark
We are the power that feeds the spark.
Strand by strand
Hand over hand
Thread by thread
We weave the web."

As the power is released, the wine representing the group's wishes is released into a bonfire, or fire burning in a central cauldron. The energy is sent out with the group saying in unison:

"With harm to none, so mote it be."

Dismissals:

Shining Lady of the night,
We thank you for sending us your blessings.
Go if you will, or stay if you wish,
But may their be peace between us always.
Hail, and farewell.

Mighty Lord of the forest,
We thank you for sending us your blessings.
Go if you will, or stay if you wish,
But may their be peace between us always.
Hail, and farewell.

To the guardians and powers of the North,
Thank you for lending your strength to our circle,
We ask now that you depart in peace.
Hail, and farewell.

To the guardians and powers of the West,
Thank you for lending your cleansing flow to our circle,
We ask now that you depart in peace.
Hail, and farewell.

To the guardians and powers of the South,
Thank you for lending your willpower to our circle,
We ask now that you depart in peace.
Hail, and farewell.

To the guardians and powers of the East,
Thank you for lending your enlightenment to our circle,
We ask now that you depart in peace.
Hail, and farewell.

The circle is taken up by walking three times around the perimiter of the circle counterclockwise (widdershins), starting in the north, while chanting:

The earth, the water, the fire, the air
Return, return, return, return.

Participants hold hands and close with group chant:

"May the circle be open but unbroken
May the peace of the Goddess be ever in your heart.
Merry meet, and merry part
And merry meet again."