Background: Previous studies on anthroposophic lifestyle and allergy show that the children have less risk of developing allergies. All studies so far have been retrospective and have included children in school age. In view of the facts that this lifestyle seems to protect children from allergies and that different symptoms of atopy have increased dramatically during the last decades it is of general interest to study this group of children more in detail. The earlier findings have now been followed up in a prospective research program ALADDIN (Assessment of Life style and Allergic Disease During Infancy), applying different approaches. One of these is to focus on stress (as measured by cortisol) as a factor that may underlie the decreased risk of allergy in children from anthroposophic families.   Aim: This thesis is based on data from the ALADDIN study focusing on influence of family lifestyle on allergy sensitization early in children’s life in relation to psychosocial factors and salivary cortisol as an indicator of stress. Methods: A total of 552 families were recruited during pregnancy or during the first month of the child´s life in two recruitment waves, 330 families between September 2004 and November 2007 and another 222 families between March 2008 and January 2011. They were recruited at anthroposophic maternal and child health care centers (MCHC) and from conventional MCHCs.  Data on demographics and exposures were obtained by questionnaires and interviews. Parental capacity to adapt to stressors was evaluated by means of the questionnaire “Sense of Coherence” (SOC; Antonovsky). Salivary samples were collected at home from the infants and both parents for analyzes of cortisol. Blood samples were obtained from the parents and from the children for analyzes of IgE. Results: Many family related characteristics differed markedly between the groups before and during pregnancy, during delivery and the first 12 months of age. Children from anthroposophic families had lower levels of salivary cortisol compared to peers from families with a more conventional lifestyle on all sampling occasions at 6 months of age and on some of the occasions at 12 and 24 months of age. There were no differences concerning cortisol between parents with different lifestyle and no significant differences concerning SOC-scores between the three lifestyle groups. An anthroposophic lifestyle was associated with a lower risk of allergic sensitization up to five years of age. This risk was partially explained by lower cortisol levels during infancy. Children in families with a partly anthroposophic lifestyle also had substantially lower risk of sensitization. Conclusion: An anthroposophic lifestyle protects from development of allergy during childhood, at least up to five years of age. This protective capacity is partly mediated by low cortisol levels during infancy but is also dependent on unknown characteristics of this lifestyle.  These results call for further studies on health related effects of an anthroposophic lifestyle.