This thesis integrated theories and concepts from organisational behaviour and investigated how organisations can motivate employees to participate in corporate volunteering initiatives, and ensure this participation leads to positive individual and organisational outcomes. The thesis consists of four studies that build on each other and explore the role of self-determination in corporate volunteering and the antecedents and consequences of self-determined forms of motivation. Volunteer motives are differentially associated to positive outcomes and our understanding of the mechanisms underlying these relationships are still unclear. The self-determination theory of motivation offers an explanation for why some motives are more strongly associated with desirable outcomes than others, thus serves an appropriate lens to extend our knowledge of this emerging phenomenon called corporate volunteering (Guntert et al., 2016).

STUDY 1 (Chapter II) was designed to address the following research questions: Can the level of employer involvement in the choice and management of a CV activity be used as the basis to meaningfully categorise CV types? Is CV motivation associated with participation in various types of CV activities?

The categorisation of employee volunteering resulted in three distinct forms of corporate volunteering (CV) types, namely company-organised, company-brokered and employee-organised corporate volunteering. The findings suggest motivational differences between various types of corporate volunteers, and between corporate and independent volunteers (volunteering without employer support). Specifically, employees who participated in company-organised volunteering did so to avoid feeling guilty or negatively about themselves, more so than those participating in employee-organised corporate volunteering. Further, independent volunteers were driven by understanding the value and importance of their contribution to the community, more so than their corporate volunteer counterparts. The findings also indicate that employees participating in corporate volunteering types with greater employer involvement, e.g. company-organised volunteering, were more likely to continue engagement in corporate volunteering in the future.

STUDY 2 (Chapter III) extended STUDY 1 and was designed to address the following research questions: Are psychological work climate-related antecedents, namely Corporate Social Responsibility (CSR) climate and perceived supervisory support for corporate volunteering (PSS) , associated with CV motivation based on the SDT? Do motivational states based on SDT relate to desirable individual and organisational outcomes of corporate volunteering (volunteering satisfaction, perceived volunteering impact, and employee organisational commitment)? Does motivation explain the positive link between work-climate related antecedents and desirable individual and organisational outcomes of CV?

The results corroborated expectations that CSR climate and PSS are positively related to autonomous forms of motivation (intrinsic and identified), which in turn are positively related to volunteering satisfaction, employee organisational commitment and employee perceived community impact efficacy. Importantly, the results also highlight the unique characteristics of intrinsic vs identified motivation, pointing to their differentiated relevance for various outcomes, and the value in exploring the individual contribution of various forms of self-determined motivations.

STUDY 3A (exploratory) and 3B (follow-up) (Chapter IV) built on the findings of STUDY 2, which identified the greater importance of autonomous forms of motivation for corporate volunteering and were designed to address the following research question: What role do various forms of rationale for CV play in motivating and recruiting corporate volunteers? These studies were designed to explore the role of communication in the promotion of corporate volunteering participation. SDT suggests that environments that support autonomy are signalled by communications that provide volunteering rationale conveyed in an autonomy supportive language (Deci et al., 1994). The exploratory study (STUDY 3A) used a convenience sample and was designed to run manipulation checks and enable the validation and fine-tuning of the wording and content of messages in corporate volunteering advertisements. In addition, this study also compared the motivational effects of various goal contents communicated in an autonomy-supportive way. The follow-up study (STUDY 3B) used an employee sample from three NZ organisations with an existing CSR strategy, and was designed to validate and extend STUDY 3A by incorporating volunteering rationale conveyed in a controlling language, and assessing perceived pressure to volunteer.

STUDY 3A results suggest that pro-social rationale was positively associated with the perception of autonomy, consequently with autonomous forms of motivation and future volunteering intentions (FVI), as compared to receiving no rationale at all.

These results suggest that in certain circumstances, messages with no rationale might be effective recruitment tools for corporate volunteering. Potential explanations for these contradictory findings are discussed in the relevant section.

In summary, the findings of this thesis emphasise the variability in corporate volunteering motivation and the fact that the type of volunteering undertaken by an employee may be a relevant factor to consider in future corporate volunteering studies, as well as for the design of corporate volunteering programs. Furthermore, if organisations want to promote self-determined forms of motivation for corporate volunteering in order to enhance related outcomes, their long-term strategic focus should entail the development and maintenance of a positive CSR climate and the provision of supervisory support for participation in these schemes. It might also be recommended that organisations tailor their recruitment messages for corporate volunteering participation by taking into account their unique organisational culture and other contextual factors.