This study examines loneliness and its correlates-health, residential care, partner status, and network size-over a seven-year period among adults born between 1908 and 1937. The four waves of data are from the Dutch Living Arrangements and Social Networks of Older Adults" and the "Longitudinal Aging Study of Amsterdam programs. Data from at least two waves are available for 2,925 respondents. Results show that older adults generally become lonelier as time passes. The increase is greater for the oldest, the partnered, and those with a better functional capacity at baseline. Older adults who lose their partner by death show the greatest increase in loneliness. Not all older adults become more lonely: Improvement in functional capacity and network expansion lead to less loneliness. Entry into residential care does not affect loneliness. The longitudinal design provides new insights into factors that protect against loneliness compared to cross-sectional studies. © 2005 Sage Publications.