Area office leasing activity, which ranks among the top three cities in nation in terms of new tenancy, included these recent transactions. Most of the leases are for Aspen System Corp. and Westat Inc. have agreed to take 60,000 square feet each in a $10 million building being completed by Glen Construction at Plaza 270 Office Center on Research Boulevard in Rockville. Norman Tyler is the developer and Holle & staff the architect. Walker & Dun [TEXT OMITTED FROM SOURCE], the leasing agent for the building, reported 90 percent preleasing a total of 160,000 square feet to be completed in two stages this summer and winter.

Alexander Grant & Co., a national accounting firm, is taking 28,000 square feet at 2000 L Street NW, were Cooperative Executive Offices taking 22,000 square feet and the [TEXT OMITTED FROM SOURCE] Packaging Institute is taking [TEXT OMITTED FROM SOURCE] square feet. The Breadon Companies, which handles lesses for the building now owned by the EJ Development Co., said all three cases are effective in September.

Congressional Information Services will double its present space by moving from 7101 Wisconsin Ave. to 40,000 square feet at 4500 East-West Hwy. in Bethesda. Julien J. [TEXT OMITTED FROM SOURCE] inc., which handled the [TEXT OMITTED FROM SOURCE], said occupancy will begin this fall.

The Urban Land Institute, a non-profit research group with an interest in development and housing, will move into 17,500 square feet of new space at 1090 Vermont Ave. NW in November under leasing arrangements made by H.G. Smithy Co. The same firm arranged for the Housing Assistance Council, which helps low-income families find affordable housing, to take 8,400 square feet in a new building at 1025 Vermont Ave. NW.

Northern Telecom, a subsidary of Bell Canada International, has signed to take 29,000 square feet at 1749 Old Meadow Rd., Tysons Corner, and 2,000 feet at 6110 Executive Blvd. in Rockville. Shannon & Luchs negotiated the leases for the tenancy, estimated together to be $1.6 million.

Wang Laboratories Inc. will triple its present space by leasing 25,000 square feet for its word-processing division at 1300 N. 17th St., Rosslyn. Coldwell Banker, which represents the tenant, said that an October move is planned into the building being leased by the Studley firm.

MCI, an expanding telecommunications firm, recently moved into 32,000 square feet at 1151 Seven Locks Rd., Bethesda. Earlier H. G. Smithy Co. also arranged for MCI to occupy 183,000 square feet in a new building being completed at 1137 19th St. NW, where January occupancy is scheduled. b