Survival in variable natural environments with (a)biotic stressors (including parasites) requires effective immunity, also for snails (Mollusca, Gastropoda). Gaining in-depth understanding of immunology across snail phylogeny is challenged by great diversity of gastropods. Focused lab research, aided by genomics, led to extensive characterization of molecular immunology of the freshwater snail Biomphalaria glabrata (family Planorbidae, Hygrophilid snails), vector of Schistosoma mansoni, human parasite. Next generation sequencing (NGS) enables immunogenomics, revealing immune gene complements in genomes of other snail species, including Lymnaeidae and Physidae, also families of Hygrophila. The mechanics of snail immune function (mostly studied in vitro, with genetically similar lab snails) can now be interpreted as some combination of specific molecules and pathways for pathogen recognition, signaling, and humoral and cellular effectors, yielding a degree of pathogen-specificity. Accordingly, snail molecular immunology can provide a resource for ecoimmunology to help identify specific immune factors and processes that aid snail survival in the field when faced with various stressors. A cage-study is in progress with different populations of mitogenome haplotype-characterized Physella acuta to compare immune transcriptomes among lab-maintained and rewilded snails. Already, NGS showed that use of particular immune pathways and effectors varies among individual Lymnaea stagnalis snails of mixed genetic background. Such studies may inform field studies of snail vectors of medical relevance and help define the realities of field immunology of snails.