To qualify for permanent resident status in any sub-category of this classification, the alien is required to have employer sponsorship and Labor Certification, or documentation to prove that the alien qualifies for one of the shortage occupation the Department of Labor has identified on a list known as "Schedule A." Schedule A occupations include physical therapists, professional nurses, physicians or surgeons, college or university teachers, aliens of exceptional ability in the sciences or arts (except performing arts), certain religious occupations, and intra company transferees in managerial or executive positions. Certain provisions of the Immigration Act of 1990 directed the Department of Labor to conduct a Labor Market Information Pilot Program to identify additional occupations for which there is a shortage of labor within the United States. Aliens in those occupations, then will be able to apply for permanent resident status under this classification must be filed by the employer on behalf of the alien.

A "skilled worker" means an alien who, at the time the petition is submitted, is qualified and capable of performing a job that requires at least two years of training or experience for which no U.S. workers are available. The job must not b of a seasonal or temporary nature. In some instances, an alien with less than two years experience may be eligible for permanent resident status under this classification if relevant post-secondary education may be considered as training.
The skilled worker's petition must be accompanied by evidence that the alien meets the educational, training, or experience, and any other requirements set forth in the approved Labor Certification application. The evidence may be in the form of letters from trainers, or previous or current employers. The letter must contain the name, address, and title of the trainer or employers, and a detailed description of the training received or the experience of the alien. If the alien seeks status under the provisions of Schedule A, or under DOL's Labor Information Pilot Program, a fully executed uncertified Form ETA-750 must accompany the I-140 Petition.

A "professional" means an alien who holds at least a U.S. baccalaureate degree or a foreign equivalent degree, and who is a member of the professions. The petition must be accompanied by an official college or university record showing the date the baccalaureate degree was awarded, and the area of concentration of study. To show that the alien is a member of the professions, the employer must submit evidence showing that the minimum of a baccalaureate degree is required for entry into the occupation .

"Other workers" are those who, at the time the petition is filed, are capable of performing unskilled labor, or labor that requires less than two years training or experience, for which U.S. workers are not available. The employment must not be of a temporary or seasonal nature. An I-140 petition for an unskilled worker must be accompanied by evidence that the alien meets any educational, training, or experience requirement of the approved Labor Certification application.