Elegant surroundings: From the Foster Brothers, Boston (c. 1910).

She installed the exhibition with visual impact rather than chronology in mind. Some of the frames are presented in nesting formats in which larger frames enclose a series of progressively smaller ones, resulting in wall montages of stunning complexity. Wall labels and the exhibition's catalog (both written by Suzanne Smeaton, director of Eli Wilner & Co.) trace the decade-by-decade evolution of taste and style in frame-making, an evolution parallel both to the history of art and to trends in architectural ornament and interior design.

Many painters, among them James McNeill Whistler, Thomas Cole, Frederic Church and Childe Hassam, were famously involved with the design of the frames that surround their pictures. Cole and Church, both Hudson River School painters, favored different styles of frames for their landscapes. The "Cole frame" is decorated with dense floral patterns in low relief, which echo and reinforce the painted areas of foliage. Church-designed frames feature geometric patterns and are often stepped, as are many 19th-century frames, in such a way as to help lead the eye into the spatial depth of the picture. In both cases, the frames play aesthetic as well as functional roles, contributing in fundamental ways to how the paintings are perceived.

Included in the exhibition is a handsome frame of the 1870s with a Moorish design of the sort employed by Church for his paintings of the Near East. Throughout the time period represented by the show, Spanish, French, Dutch, Italian and other influences come and go, often reinterpreted to suit particular subject matters and American tastes.

Most 19th-century American frames consist of wooden substrates embellished with applied ornament known as "compo" - a moldable substance that dried hard and was gilded in the same way as carved wood. Although most of the 19th-century frames in the exhibition are listed as "Maker: Unknown," a few of the most intricately conceived and beautiful ones were designed in the 1890s by the architect Stanford White, who created frames for such artist friends as Augustus Saint-Gaudens and Thomas Wilmer Dewing. Included in the exhibition is a wide, flat frame, golden-brown in tone, ornamented with row after row of concentric bands so narrow that the whole resembles an assembly of gold chains of different widths and patterns laid side by side. The ornamental patterns - among them classical egg and dart, a wave pattern, a braid and twisted bands - were arranged to suggest contrasting directions and speeds of movement. The picture it once graced is today unknown.

After the turn of the 20th century, the use of applied compositional ornament was shunned in favor of hand carving, a return to tradition influenced by the Arts and Crafts Movement in Britain. A leading figure was the artist and frame maker Hermann Dudley Murphy, through whose Boston studio, Carrig Rohane, passed a number of the leading frame designers of the day. All skilled woodcarvers, they are represented in the exhibition by works of remarkable variety in style, composition and handling. In 1908, for example, Murphy produced two dramatically contrasting frames. One is an extravagant oval shape carved with a bold but graceful curvilinear pattern, and the other is a rectangle with a handsome outer band that encloses a stepped pattern of complex rhythms.

The Simoni Collection reveals the American period frame as a decorative art object rich in history and worthy of contemplation. A number of the frames are so aesthetically powerful that for them to be paired with paintings at this point would result in difficult marriages indeed. In the ideal marriage, the frame and painting complement and enhance one another, each showing the other to best advantage.

Ms. Simoni now buys only one or two frames a year, mostly to fill gaps in her collection. Today, frames of the quality of those found in the collection can sell for as much as $200,000. No longer relegated to a supporting role, the American period frame has become a star.