This study attempts to describe, in a comparative way, scientific collaboration and co-authoring activities and understanding of Brazilian researchers of productivity level 1 at the National Counsel of Technological and Scientific Development (CNPq). In order to do so, a questionnaire was sent to the researchers of productivity level 1 at CNPq in the Mathematics, Dentistry and Information Science fields, with questions about scientific collaboration and co-authoring activities. We analyzed the scientific production of the researchers who answered the questionnaire and we have identified that 78% of the participants consider that scientific collaboration and co-authorship are different activities, and the potential and usual number of research collaborators is between 2 and 3 in Mathematics and Information Science, and between 5 and 6 collaborators in Dentistry. Differences among fields were pointed out by identifying main collaborators and co-authors. The reasons for collaborating vary according to the nature of the research, however, the percentages are high in these three areas: ''training of researchers and students'', ''desire to increase their own experience through the experience of others'' and ''increased productivity.'' From the analysis of the scientific production declared in their Lattes Curriculum, we have found that the average number of authors per publication in the field of Information Science is 2.2 authors, in Mathematics is 2.8 authors per publication, and in Dentistry the average is 5.3 authors per publication. We have concluded that scientific collaboration and co-authorship are terms assigned to different activities for the analyzed fields.