"Smart growth." It sounds great, but it can end up looking like dumb growth if smart design isn't part of it.

Smart-growth policies aspire to create attractive, sustainable communities by using existing infrastructure efficiently, promoting compact development and preserving natural resources. Through public investment and anti-sprawl regulation, the pace and location of growth can be improved.

But to achieve truly smart growth, it is not enough simply to map out where land can and cannot be developed. Smart design must prescribe patterns of land use, density and movement in more detail and determine how street networks, parks and buildings will be configured and woven together.

To see both smart growth and smart design in action, you have to visit Portland, Ore. Perhaps America's most successful growth management and urban design model, Portland is the product of enlightened judgment applied over many decades to wisely accommodate growth within a beautiful landscape.

Oregon is well known for pioneering statewide growth management. In 1973, the state adopted legislation mandating that each city and county cooperatively establish an urban growth boundary, or UGB.

A UGB encompasses already urbanized areas, plus undeveloped land to accommodate 20 years of new growth. Outside a UGB, land can be used only for agriculture, forestry or sparse rural residential development. Modifying a UGB requires rigorous justification, and new land within the relocated boundary must be adjacent to existing development and served by adequate public infrastructure.

Not surprisingly, Oregon's UGB policy yields higher-density development--multifamily housing and smaller house lots. It also can push up real estate prices when developable land supply tightens relative to market demand. But periodic statewide referenda have shown that a majority of Oregon's predominantly middle-class citizens strongly favor smart growth.

Portland's design wisdom was evident long before statewide growth management came along. The city has been doing things smartly ever since its founding in the 1840s by a pair of New Englanders, Amos Lovejoy of Boston and Francis Pettygrove of Portland, Maine. By the flip of a coin, the latter won the right to name the city after his hometown.

Situated about 60 miles inland at the confluence of the Willamette and Columbia rivers, Portland lies in a broad, hilly valley flanked by two mountain chains, the Cascade Range to the east and the Coast Range to the west. Because the Columbia River is navigable, Portland is, in fact, a major port city accessible to ocean-going ships.

During the 19th century, its favorable location and natural amenities attracted growth that was spurred by increased trade, lumbering, agriculture, discovery of gold and arrival of the railroad.

Today you can still see the admirable urbanization geometry first imposed on the clearing in the woods where the settlement began. Among the most memorable characteristics of this geometry are the unique street grid pattern and the small city blocks that result.

Downtown Portland's typically square blocks measure only 200 feet on a side, much smaller than blocks in most other American cities. These small-scale blocks offer several benefits.

* The number and frequency of streets that make up the grid substantially increase traffic capacity in all directions. During rush hours, timed signals allow vehicles to flow more efficiently across the grid.

* Shorter blocks make walking more pleasant, despite more street crossings. Each intersection is a psychological way station, a way for pedestrians to sense progress during their journey on foot.

* Portland's streets, typically only a few lanes wide, are flanked by sidewalks and the thick canopies of shade trees. This produces an intimate streetscape, even with high-rise buildings towering above.

* Small blocks mean more street-fronting perimeter for each building, more corner windows for a greater percentage of tenants and, especially valuable downtown, more sidewalk-level frontage for retail and commercial uses. Many of Portland's blocks are occupied by only one building.

* Small blocks preclude mega-buildings--edifices can soar but not spread--or land assembly for gargantuan complexes within the city center. No Department of Commerce or Ronald Reagan Building could fit into the middle of Portland. However, pedestrian bridges occasionally span streets to link buildings on adjacent blocks, and a 600-foot-long central-city parking garage jumps across two streets, preserving street grid continuity.

An equally memorable feature of Portland's cityscape legacy is its parks. Calling itself the "City of Roses," Portland has been the beneficiary of open-space preservation and generous gifts of land dating back to the 19th century. Today it has more than 200 parks, including 4,800-acre Forest Hills Park. Thanks to the flexibility of the street-block grid, there are numerous urban half-block, full-block and linear parks woven tightly into the cityscape.

Stretching for a mile along the Willamette River, downtown Portland's eastern edge, is Governor Tom McCall Waterfront Park, a tribute to the city's historical willingness to do the right thing. In 1974, a freeway occupying the waterfront was plowed under to reconnect the city to its now cleaned-up river. Walking along the park promenade to enjoy the view and fresh air--the result of hydroelectric power generation and absence of smokestack industries--I couldn't help thinking about Washington and what Georgetown's waterfront might have become had the Whitehurst Freeway been removed.

Of course, Portland has not neglected its transportation systems. Like many other American metropolises, interstate freeways snake through the city, along with a light rail line.

There are designated historic districts with architecturally distinct 19th and early 20th century buildings clad in brick, cast iron and terra cotta. And there is plenty that's new: modern office towers, a convention center, a science museum, maritime and fire museums, and one of the world's great bookstores, Powell's City of Books, reportedly with more than 1 million book titles in its inventory.

Intelligent growth and urban design explains why Portland is considered such a desirable place to live and to emulate in other cities. It's also why many Oregonians want to keep it all a secret.

Roger Lewis is a practicing architect and a professor of architecture at the University of Maryland.