Biofilms are surface-attached microbial communities. c-di-GMP is a conserved dinucleotide signal that regulates biofilm formation by bacteria. In Pseudomonas fluorescens, a critical pathway for biofilm formation requires the localization of a larger cell surface adhesion, called LapA, to the cell surface.  Localization of LapA is regulated by the dinucleotide signaling molecule c-di-GMP.  Synthesis of c-di-GMP by diguanylate cyclases (DGCs) and its degradation by phosphodiesterases (PDEs) is well established, and progress has also been made in elucidating c-di-GMP output systems. For example, our group has characterized a membrane protein, LapD, which binds c-di-GMP via a degenerate PDE domain; this c-di-GMP receptor regulates localization of the LapA adhesin to the cell surface, which is a critical event for biofilm formation by P. fluorescens. A central open question in the field is how bacteria like P. fluorescens and P. aeruginosa, with 50+ proteins that make, break and bind c-di-GMP, coordinate the action of these many proteins to provide a coordinated, c-di-GMP-regulated output.  I will discuss two aspects of recent work from the lab: (i) explore mechanisms of c-di-GMP signaling specificity that impact the control of a biofilm adhesin system that is conserved in 500+ bacterial genomes, (ii) describe recent findings demonstrating a novel mechanism whereby the c-di-GMP-regulated adhesin LapA is localized to the surface.