Understanding the antecedents and consequences of trust in an online and on-demand outsourcing context is important. This study explores the effects of service quality on trust, which in turn affects a client firm’s post-adoption use in SaaS. A research model was developed based on the dedication-constraint framework of social exchange theory to measure service quality, trust, and SaaS post-adoption as multiple dimensions. We empirically examined the model by collecting data from 246 firms (key informants) that have adopted SaaS. Results show that while all three dimensions of service quality (client orientation quality, client response quality, environment quality) positively affect trust in service quality, client orientation and environment quality have positively influence on trust in provider. Both types of trust positively influence post-adoption intention. Finally, we discuss the theoretical and practical implications.