Ten years after the manifestation of the Miraculous Medal to Sister Catherine Laboure in 1830, the Blessed Mother entrusted the Green Scapular of the Immaculate Heart to Sister Justine Bisqueyburu, likewise a Daughter of Charity of St. Vincent de Paul. 

The manner of using the Scapular was indicated by the Blessed Virgin. Since it is not the badge of a confraternity but simply a double image attached to a single piece of cloth and suspended from a cord, investiture is not required. It suffices that it be blessed by a priest and worn by the one for whom it is intended. It may be placed in the clothing, on the bed, or simply in the room. 

The only prayer is the inscription surrounding the heart on the reverse of the Scapular:"Immaculate Heart of Mary, pray for us now and at the hour of our death." Although wonderful graces are obtained, they are proportionate to the confidence with which it is given. 

The Green Scapular was twice approved by Pope Pius IX, in 1863, and again in 1870, when he said: "Write to these good Sisters that I authorize them to make and distribute it." 

Practices

1. Wear or carry the scapular 

2. To help another, place it in their vicinity (i.e. their room)

3. Pray, at least daily: "Immaculate Heart of Mary, pray for us now and at the hour of our death." 

4. The prayer should be said for oneself and separately for each person to whom it has been given     (unless they pray themselves)

5. No enrollment of any kind is necessary, but each scapular should be blessed by a priest (general     blessing of sacramentals) 

6. Have confidence in the effects of the scapular:

    "The greatest graces come from using the scapular but these graces come in direct proportion to       the degree of confidence in me which the user has." 

Promises/Benefits

1. Conversion of those who do not have the faith

2. Reconciliation to the Church for those who have lost/strayed from the faith 

3. Assurance of a happy death

4. Strengthening of the faith for those already in the Church

5. Protection from Satan for those who wear or promote the scapular

(You may go to http://www.catholictradition.org/Mary/green-scapular.htm for more details)