This paper explores the advantages and disadvantages of combining data from GPS units and SMS's from mobile phones, when exploring the mobility of families. Building on experiences from a research project aimed at investigating the mobility of approximately 50 families in Copenhagen, the capital of Denmark, this paper adds to our knowledge about how quantitative information about trips gathered from GPS units and qualitative information from SMS's sent by the respondents describing their experiences of their trips, can be combined. It is argued, that SMS's holds the advantage, that they are able to capture the feelings of the respondents "here and now" while they are on a trip. Therefore data on mobility collected this way holds certain advantages compared to for example data on mobility gathered through questionnaires. On the other hand, the use of SMS data also poses certain challenges, and these are for example how complex questions the respondents can answer through SMS's and how respondents can be motivated to send SMS's during their daily routines. This methodological discussion of the strengths and weaknesses of the combination of GPS data and SMS data in this paper is of value to all researchers within the mobility field, who contemplates using GPS technology in their research.