Boston College saw a 26-percent decrease in applications this year, a drop officials largely attribute to a new essay requirement. Last year the private Jesuit institution received a record 34,051 applications for 2,250 spots in its freshman class. This year approximately 25,000 students applied, and all of them had to do one thing their predecessors did not: write a supplemental essay, of up to 400 words, in response to one of four prompts. Although some enrollment officials have nightmares about big one-year declines, John L. Mahoney, director of undergraduate admissions at Boston College, described the numbers as good news. After all, the quality of this year's applicants--as measured by their ACT and SAT scores--did not go down, compared with last year. In an era when many colleges are asking applicants to do less, some institutions have asked them to do more, purposely thinning the ranks of prospective students. If nothing else, Boston College's move reveals the slipperiness of application tallies, widely viewed as a meaningful metric. If the addition of one short essay can drain a quarter of a college's pool in one year, how much did those numbers say in the first place? For the last decade, selective colleges have operated according to their own laws of nature: Each year, applications rise, acceptance rates fall, and the trends seem as inevitable as gravity. In the competition for high-achieving students, bigger applicant pools have long been understood as better. And "more, more, more" is often the mantra of recruitment. The boom has brought plenty of challenges, too. A deluge of applications has made the admissions process less predictable, for applicants and colleges alike. More students applying to more colleges means more questions about who's a serious applicant and who's not. Some of the forces that have long driven application increases were beyond any college's control. The long-term surge in high-school graduates. The rise in foreign applicants. The growth of Web-based communications. Yet colleges do control the content of their applications, and how quickly a student can apply.