In 1997, 11.5 percent of the employed U.S. scientific and engineering (S&E) workforce held second jobs[1]. Because those with second jobs constitute such a significant fraction of working scientists and engineers, it is useful to examine their employment and demographic characteristics, as well as to begin to understand the motivation of these individuals to work in second jobs. Table 1 shows the percentages of those who had second jobs in the three main employment sectors: education, government, and business/industry. The percentage of those with second jobs was highest for those whose primary job was in the education sector and lowest for those primarily working in business or industry. There was some variation within and among employment sectors: employees of private not-for-profit organizations and State and local governments were roughly twice as likely to hold second jobs than those working in the private, for-profit sector (16.1 to 16.4 percent versus 8.6 percent). Among those whose principal job was part time, 18.3 percent held second jobs, compared with only 10.0 percent of individuals who worked full time on their principal job[2]. The percentage of S&Es with second jobs was lower for those who supervise others (10.5 percent) than for those who did not (12.4 percent).

Some 21.6 percent of social scientists[3] worked in second jobs, the highest rate by occupational group within the S&E workforce (table 2); engineers participated in second jobs at the lowest rate (7.1 percent)[4]. Individuals with S&E principal jobs who held second jobs did not tend to work in the same occupations as that of their principal job. With the exception of social scientists and individuals in non-S&E occupations, only about a third of the science and engineering workforce with second jobs held them in the same occupational group as their primary jobs. For those with second jobs in a category different from their principal job, the second job was most likely in the category of a non-S&E occupation. Between 52.8 and 61.3 percent of those principally employed in computer or mathematical sciences, physical sciences, life sciences, and engineering who held second jobs worked in second jobs that were not in science and engineering.

What factors are related to holding a second job? Dissatisfaction with the principal job did not appear to be an important factor: 11.1 percent of individuals who were "very" or "somewhat" satisfied with their principal jobs obtained second jobs compared to 14.0 percent of individuals who were "very" or "somewhat" dissatisfied with their principal jobs. Similarly, the relationship of an individual's highest degree to his or her principal job was a minor factor: those with second jobs were only slightly less likely (76.9 percent) to report that their highest degree is related to their principal job versus those without second jobs (78.4 percent).

However, individuals with second jobs reported that their second jobs were more likely to not be related to their highest degree than their principal jobs (42.2 versus 23.1 percent) (table 3). The greater the level of the highest degree, the more likely it was that an individual held a second job: 10.5 percent of bachelor's degree holders, 12.4 percent of master's degree holders, and 15.1 percent of doctorate holders worked in second jobs (table 4).

Income and salary on the principal job may be factors in the decision to hold a second job. Individuals with a second job reported that their median salary on their principal job was $39,000; those without second jobs reported a median salary of $49,000 on their principal jobs. This gap closed somewhat when total earned income was considered: the total median earned income of those with second jobs was $45,000 compared with $50,000 for those without second jobs. Total household income was also lower for those with second jobs, $65,000, as opposed to the $74,000 reported for those without second jobs.

Table 4 relates demographic characteristics of employed scientists and engineers to the likelihood of holding a second job. A slightly higher percentage of women (12.1 percent) than men (11.2 percent) were employed in second jobs. Persons with disabilities were slightly more likely to have second jobs (13.0 percent) than those without disabilities (11.4 percent). Among the racial/ethnic groups, Asian/Pacific Islanders were the least likely to hold a second jobs (7.8 percent); blacks and Native American/Alaskan Natives were most likely to hold such positions (15.2 and 14.1 percent, respectively). As a group, underrepresented minorities were slightly more likely to hold second jobs (14.0 percent) than were Asian/Pacific Islanders and whites (11.2 percent). Some 9.1 percent of permanent residents and 4.1 percent of temporary residents held second jobs, compared to 11.6 percent of U.S. citizens. This difference may be partially attributable to visa status: holders of temporary visas require full-time employment to be granted a visa, and may be restricted from holding another job.

The propensity of U.S. scientists and engineers to be engaged in second jobs did not change much over the middle years of the decade of the 1990s, as shown in table 5. There were some fluctuations over two year periods in the percentage of individuals who held second jobs, with a 6.7-percent decrease in the period from 1993 (11.9 percent) to 1995 (11.1 percent).

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