Purpose: to examine the combined effect of cohabitation status and social participation, respectively, and socioeconomic position on onset of mobility limitations in a prospective study among older Danes. Design and methods: logistic regression analyses with combined exposure variables were performed in a study population of 2,839 older men and women from the Danish Intervention Study on Preventive Home Visits. Results: among men low financial assets, living alone or having low social participation significantly increased the odds ratios (OR) for onset of mobility limitations. Among women only low financial assets and low social participation significantly increased the ORs for onset of mobility limitations. Analyses with combined exposure variables showed that simultaneous exposure to low financial assets and poor social relations significantly increased the ORs for onset of mobility limitations among both genders, yet the tendencies appeared stronger for males. In particular, men with simultaneous exposure to low financial assets and low social participation had increased odds ratios for onset of mobility limitations, OR = 5.36 (2.51-11.47), compared with the non-exposed. Conclusion: the study suggests that future interventions to increase social participation might alleviate the negative effects on mobility experienced by older people in low socioeconomic position, perhaps especially among older males.