This was published as a Wall Street Journal Think Tank column on July 21, 2014.

The Affordable Care Act’s success meeting its initial enrollment goals and the repair of HealthCare.gov seem to have calmed the political waters for Obamacare. But the job of enrolling the uninsured gets harder, not easier, because the remaining uninsured will generally be tougher to reach.

Recent surveys show, roughly in line with expectations, that 8 million to 9.5 million fewer adults are uninsured compared with last year before the Affordable Care Act went into effect. Specific data are not yet available for uninsured children who probably got covered as well, and an earlier provision of the health-care law that allowed people to stay on their parents’ insurance up to age 26 is thought to have lowered the number of uninsured young adults by as many as 3 million.

But tens of millions of Americans are not yet covered.

Those who enrolled last year during the first open-enrollment season were more likely to want coverage and were best able to navigate the process to get it. After open enrollment this fall and the one after that, the uninsured will gradually become a smaller and different group. Increasingly, they will be people who have been without insurance for a long time or who have never had it; people who are even less familiar with insurance choices and components such as premiums and deductibles, as well as unfamiliar with the tax credits offered under the ACA. These people are more likely to be men, and minorities, and have limited education or language barriers. Increasingly they will fall into harder-to-reach high-risk groups, such as the homeless, who require very targeted outreach, and Hispanics who fear that seeking coverage could endanger undocumented relatives despite assurances from government that it will not.

On the plus side for the next open-enrollment season, many of the remaining uninsured waited out the first year but want insurance; a group of unknown size has been waiting to enroll this fall. Also, the penalties for not having insurance rise from the greater of $95 per adult or 1% of income this year to $325 or 2% of income next year. That is likely to motivate more of the remaining uninsured to enroll. Early studies show that the uninsured who have attained coverage are happy with what they got, and news will spread through family, friends and word of mouth to people who are uninsured, motivating some of them to seek coverage too.

As the job of reaching the uninsured gets tougher, the need will grow for targeted community-based outreach and enrollment services and, most of all, a realization that the remaining uninsured are a somewhat different group presenting new challenges.