While the traditional color for Advent is purple, there is a growing interest in and acceptance of the color blue as an alternative. The United Methodist Book of Worship identifies purple or blue as appropriate colors for Advent (224, 226, 238).
This has led to some confusion and many questions among worship leaders. Many churches have invested significant dollars in purple paraments that serve both for Lent and Advent. Some wonder if this is some kind of marketing ploy by supply houses to sell an additional set of paraments. Most are simply puzzled by the introduction of a color not traditionally associated with liturgical colors.
The genesis of the introduction of blue into the liturgical colors comes from continued reflection on the calendar of the Christian year, particularly on the season of Advent. Here is how the reasoning goes: Advent is a season of preparation that anticipates both Bethlehem and the consummation of history in the second coming of Jesus Christ. Since this anticipation is characterized by hope -- in contrast to the repentance characteristic of Lent -- the color for the season should not be purple, with its mood of solemnity and somberness, but blue with its hopefulness. Admittedly, there is a some subjectivity in linking colors with certain moods.
There is precedent for the use of blue during Advent. The Swedish Church and the Mozarabic rite (the rite used in the parts of Spain under Moorish rule from the eighth to the twelfth centuries) used blue.
In considering which color to use, keep in mind that the standardization of colors is a fairly recent phenomenon in the church and that a scheme of colors is still evolving. The latitude of The United Methodist Book of Worship suggests that we are a part of this ongoing process. The Evangelical Lutheran Church in its 1978 Lutheran Book of Worship lists blue as the preferred color for Advent, but leaves purple as an option.
The rule of thumb here is this: Your congregation may use either color. If you just bought purple paraments, enjoy them and wait for a memorial gift sizable enough to buy blue ones later. If your paraments are in poor repair and need replacement, or if there are no paraments for your worship space, consider blue as the color for use during Advent and purple for use during Lent.