Purpose – The purpose of this paper is to investigate the extent to which the accessibility of established parent brand information and the diagnosticity of newly launched horizontal and upward service line extensions affect transfer and reciprocal transfer of brand associations. Design/methodology/approach – A field study using a survey methodology based on a 2×2 experimental random design was conducted with a sample representative of the target population of an established bank in Eastern Canada. Two levels of parent brand accessibility (high/low) and two levels of line extension (upward/horizontal) were tested. Pretests were conducted, and the analysis of results was done using a three-point-in-time confirmatory factorial analysis for each cell. Findings – The findings indicate that for a newly launched horizontal service line extension, when accessibility of an established parent brand is high, information transfer and reciprocal transfer of brand associations is strong and complete. When accessibility is low, transfer is strong but incomplete, leading to partial dilution of the parent brand. In the case of a newly launched upward service line extension, for both high- and low-accessibility contexts, only key diagnostic parent brand associations transfer to the extension. Reciprocal transfer is strong, leading to a significant dilution of the parent brand. Research limitations/implications – Other kinds of extensions (e.g. downward, distant), other types of services, and consumer goods could be tested to observe the extent to which transfer works. Practical implications – This study provides key findings to managers who are responsible for launching newly created service line extensions (horizontal and upward). When evaluating a new vertical service line extension, consumers actively process the available information at hand (e.g. print advertising, point-of-purchase materials), but key diagnostic associations of the parent brand tend to persist over time. Thus, marketers must be careful when using or not using parent brand information during launch, though an upward service line extension is likely to dilute the parent brand’s equity, either positively or negatively. Originality/value – This paper brings new insights to the service branding literature with respect to the dynamics of transfer of brand associations between service line extensions (horizontal and upward) and their parent brands. Drawing on the accessibility-diagnosticity framework, it closes an important theoretical knowledge gap regarding the persistence over time of accessible vs diagnostic parent brand information in the mechanisms of transfer of brand associations to and from different types of service extensions.